Delete an existing dynamic audio data playback buffer.
'bufferhandle' is the handle for the buffer to delete. If it is omitted, all
buffers will be deleted. 'waitmode' defines what happens if a buffer shall be
deleted that is currently in use, i.e., part of the audio playback schedule of
an active audio device. The default of zero will simply return without deleting
the buffer. A setting of 1 will wait until the buffer can be safely deleted.