The CLEAR (abbreviated CL) command deletes a buffer.

Format: CLEAR buffer

The buffer no longer appears on the list printed by SHOW BUFFER.  If the
buffer was a macro, it is no longer a macro.  If the buffer contained any
text, that text is deleted.  If that buffer was the current buffer, the
current buffer becomes MAIN.  There are two exceptions to these rules: the
buffers PASTE and MAIN.  The CLEAR command does not delete these buffers but
just deletes their text.  Note that the argument is a buffer name, not a range
specification:  CLEAR PASTE is valid, while CLEAR =PASTE and CLEAR BUFFER
PASTE are not.