This function releases a thread local storage (TLS) index, making it available for reuse.
Nonzero indicates success. Zero indicates failure. To get extended error information, call GetLastError.
If the threads of the process have allocated dynamic storage and used the TLS index to store pointers to this storage, they should free the storage before calling TlsFree.
The TlsFree function does not free dynamic storage that has been associated with the TLS index.
It is expected that DLLs only call this function during their process detach routine.
For a brief discussion of typical uses of the TLS functions, see the Remarks section of the TlsAlloc function.