diff --git a/flagcx/adaptor/adaptor.h b/flagcx/adaptor/adaptor.h
index 2684c0f..116bb15 100644
--- a/flagcx/adaptor/adaptor.h
+++ b/flagcx/adaptor/adaptor.h
@@ -64,12 +64,6 @@ struct flagcxCCLAdaptor {
     // Group semantics
     flagcxResult_t (*groupStart)();
     flagcxResult_t (*groupEnd)();
-
-    // Memory functions
-    flagcxResult_t (*memAlloc)(void** ptr, size_t size);
-    flagcxResult_t (*memFree)(void *ptr);
-    flagcxResult_t (*commRegister)(const flagcxHomoComm_t comm, void* buff, size_t size, void** handle);
-    flagcxResult_t (*commDeregister)(const flagcxHomoComm_t comm, void* handle);
 };
 
 const int MAX_VENDOR_LEN = 128;
@@ -122,4 +116,4 @@ struct flagcxDeviceAdaptor {
 } // end extern "C"
 #endif
 
-#endif // end include guard
\ No newline at end of file
+#endif // end include guard
diff --git a/flagcx/adaptor/cncl_adaptor.cc b/flagcx/adaptor/cncl_adaptor.cc
index 42264e2..03a4942 100644
--- a/flagcx/adaptor/cncl_adaptor.cc
+++ b/flagcx/adaptor/cncl_adaptor.cc
@@ -240,28 +240,6 @@ flagcxResult_t cnclAdaptorGroupEnd() {
     return (flagcxResult_t)c2f_ret_map[cnclGroupEnd()];
 }
 
-flagcxResult_t cnclAdaptorMemAlloc(void** ptr, size_t size) {
-    cnrtMalloc(ptr, size);
-    return flagcxSuccess;
-}
-
-flagcxResult_t cnclAdaptorMemFree(void *ptr) {
-    cnrtFree(ptr);
-    return flagcxSuccess;
-}
-
-flagcxResult_t cnclAdaptorCommRegister(const flagcxHomoComm_t comm, void* buff,
-                                       size_t size, void** handle) {
-    //return (flagcxResult_t)cnclCommRegister(comm->base, buff, size, handle);
-    return flagcxUnhandledDeviceError;
-}
-
-//TODO: unsupported
-flagcxResult_t cnclAdaptorCommDeregister(const flagcxHomoComm_t comm, void* handle) {
-    //return (flagcxResult_t)cnclCommDeregister(comm->base, handle);
-    return flagcxUnhandledDeviceError;
-}
-
 struct flagcxCCLAdaptor cnclAdaptor = {
   "CNCL",
   // Basic functions
@@ -293,12 +271,7 @@ struct flagcxCCLAdaptor cnclAdaptor = {
   cnclAdaptorRecv,
   // Group semantics
   cnclAdaptorGroupStart,
-  cnclAdaptorGroupEnd,
-  // Memory functions
-  cnclAdaptorMemAlloc,
-  cnclAdaptorMemFree,
-  cnclAdaptorCommRegister,
-  cnclAdaptorCommDeregister
+  cnclAdaptorGroupEnd
 };
 
 #endif // USE_CAMBRICON_ADAPTOR
diff --git a/flagcx/adaptor/ixnccl_adaptor.cc b/flagcx/adaptor/ixnccl_adaptor.cc
index 8113721..1034d25 100644
--- a/flagcx/adaptor/ixnccl_adaptor.cc
+++ b/flagcx/adaptor/ixnccl_adaptor.cc
@@ -182,23 +182,6 @@ flagcxResult_t ixncclAdaptorGroupEnd() {
     return (flagcxResult_t)ncclGroupEnd();
 }
 
-// flagcxResult_t ixncclAdaptorMemAlloc(void** ptr, size_t size) {
-//     return (flagcxResult_t)ncclMemAlloc(ptr, size);
-// }
-
-// flagcxResult_t ixncclAdaptorMemFree(void *ptr) {
-//     return (flagcxResult_t)ncclMemFree(ptr);
-// }
-
-// flagcxResult_t ixncclAdaptorCommRegister(const flagcxHomoComm_t comm, void* buff,
-//                                        size_t size, void** handle) {
-//     return (flagcxResult_t)ncclCommRegister(comm->base, buff, size, handle);
-// }
-
-// flagcxResult_t ixncclAdaptorCommDeregister(const flagcxHomoComm_t comm, void* handle) {
-//     return (flagcxResult_t)ncclCommDeregister(comm->base, handle);
-// }
-
 struct flagcxCCLAdaptor ixncclAdaptor = {
   "IXNCCL",
   // Basic functions
@@ -230,12 +213,7 @@ struct flagcxCCLAdaptor ixncclAdaptor = {
   ixncclAdaptorRecv,
   // Group semantics
   ixncclAdaptorGroupStart,
-  ixncclAdaptorGroupEnd,
-  // Memory functions
-  NULL,
-  NULL,
-  NULL,
-  NULL
+  ixncclAdaptorGroupEnd
 };
 
 #endif // USE_ILUVATAR_COREX_ADAPTOR
diff --git a/flagcx/adaptor/nccl_adaptor.cc b/flagcx/adaptor/nccl_adaptor.cc
index 1f98c89..72cf3b8 100644
--- a/flagcx/adaptor/nccl_adaptor.cc
+++ b/flagcx/adaptor/nccl_adaptor.cc
@@ -182,23 +182,6 @@ flagcxResult_t ncclAdaptorGroupEnd() {
     return (flagcxResult_t)ncclGroupEnd();
 }
 
-flagcxResult_t ncclAdaptorMemAlloc(void** ptr, size_t size) {
-    return (flagcxResult_t)ncclMemAlloc(ptr, size);
-}
-
-flagcxResult_t ncclAdaptorMemFree(void *ptr) {
-    return (flagcxResult_t)ncclMemFree(ptr);
-}
-
-flagcxResult_t ncclAdaptorCommRegister(const flagcxHomoComm_t comm, void* buff,
-                                       size_t size, void** handle) {
-    return (flagcxResult_t)ncclCommRegister(comm->base, buff, size, handle);
-}
-
-flagcxResult_t ncclAdaptorCommDeregister(const flagcxHomoComm_t comm, void* handle) {
-    return (flagcxResult_t)ncclCommDeregister(comm->base, handle);
-}
-
 struct flagcxCCLAdaptor ncclAdaptor = {
   "NCCL",
   // Basic functions
@@ -230,12 +213,7 @@ struct flagcxCCLAdaptor ncclAdaptor = {
   ncclAdaptorRecv,
   // Group semantics
   ncclAdaptorGroupStart,
-  ncclAdaptorGroupEnd,
-  // Memory functions
-  ncclAdaptorMemAlloc,
-  ncclAdaptorMemFree,
-  ncclAdaptorCommRegister,
-  ncclAdaptorCommDeregister
+  ncclAdaptorGroupEnd
 };
 
 #endif // USE_NVIDIA_ADAPTOR
diff --git a/flagcx/flagcx.cc b/flagcx/flagcx.cc
index f848153..ec2ae59 100644
--- a/flagcx/flagcx.cc
+++ b/flagcx/flagcx.cc
@@ -424,47 +424,3 @@ flagcxResult_t flagcxGroupEnd() {
     }
     return flagcxHeteroGroupEnd();
 }
-
-flagcxResult_t flagcxStreamCreate(flagcxStream_t *stream) {
-    return deviceAdaptor->streamCreate(stream);
-}
-
-flagcxResult_t flagcxStreamSynchronize(flagcxStream_t stream) {
-    return deviceAdaptor->streamSynchronize(stream);
-}
-
-flagcxResult_t flagcxStreamDestroy(flagcxStream_t stream) {
-    return deviceAdaptor->streamDestroy(stream);
-}
-
-flagcxResult_t flagcxMemAlloc(void** ptr, size_t size) {
-    if (is_homo_comm()) {
-        return cclAdaptor->memAlloc(ptr, size);
-    }
-    // TODO: to be implemented.
-    return flagcxNotSupported;
-}
-
-flagcxResult_t flagcxMemFree(void *ptr) {
-    if (is_homo_comm()) {
-        return cclAdaptor->memFree(ptr);
-    }
-    // TODO: to be implemented.
-    return flagcxNotSupported;
-}
-
-flagcxResult_t flagcxCommRegister(const flagcxComm_t comm, void* buff, size_t size, void** handle) {
-    if (is_homo_comm()) {
-        return cclAdaptor->commRegister(comm->homo_comm, buff, size, handle);
-    }
-    // TODO: to be implemented.
-    return flagcxNotSupported;
-}
-
-flagcxResult_t flagcxCommDeregister(const flagcxComm_t comm, void* handle) {
-    if (is_homo_comm()) {
-        return cclAdaptor->commDeregister(comm->homo_comm, handle);
-    }
-    // TODO: to be implemented.
-    return flagcxNotSupported;
-}
diff --git a/flagcx/include/flagcx.h b/flagcx/include/flagcx.h
index 18affaf..c6cf280 100644
--- a/flagcx/include/flagcx.h
+++ b/flagcx/include/flagcx.h
@@ -101,13 +101,6 @@ flagcxResult_t flagcxHandleInit(flagcxHandlerGroup_t* handler);
 
 flagcxResult_t flagcxHandleFree(flagcxHandlerGroup_t handler);
 
-/* Malloc and free function for all types of FLAGCX optimizations
- * (e.g. user buffer registration). The actual allocated size might
- * be larger than requested due to granularity requirement. */
-flagcxResult_t flagcxMemAlloc(void** ptr, size_t size);
-
-flagcxResult_t flagcxMemFree(void *ptr);
-
 /* Return the version of the FlagCX library in the supplied integer.
  * It contains the underlying adaptor library version and FlagCX core version
  */
@@ -163,12 +156,6 @@ flagcxResult_t flagcxCommGetDeviceNumber(const flagcxComm_t comm, int* device);
 /* Returns the user-ordered "rank" associated with the communicator. */
 flagcxResult_t flagcxCommUserRank(const flagcxComm_t comm, int* rank);
 
-/* Register device-side buffer for zero-copy operation */
-flagcxResult_t flagcxCommRegister(const flagcxComm_t comm, void* buff, size_t size, void** handle);
-
-/* Deregister device-side buffer */
-flagcxResult_t flagcxCommDeregister(const flagcxComm_t comm, void* handle);
-
 /*
  * Collective communication operations
  *
@@ -354,25 +341,6 @@ flagcxResult_t flagcxGroupStart();
  */
 flagcxResult_t flagcxGroupEnd();
 
-/*
- * Stream semantics
- */
-
-/*
-* Stream Create
-*/
-flagcxResult_t flagcxStreamCreate(flagcxStream_t *stream);
-
-/*
-* Stream Synchronize
-*/
-flagcxResult_t flagcxStreamSynchronize(flagcxStream_t stream);
-
-/*
-* Stream Destroy
-*/
-flagcxResult_t flagcxStreamDestroy(flagcxStream_t stream);
-
 #ifdef __cplusplus
 } // end extern "C"
 #endif