This function is not yet fully documented. This is a transcript of the text-formatted help.

bbclear   Clear black-box operator from memory.
   Most operators can be removed with a normal clear instruction.
   However, certain special operators (e.g. bbcount) needs to keep
   additional information in global variables.

   Unless you use bbclear to remove such operators, the global
   variables will be left orphaned.

   Limitation: if you made copies of cleared operators, they may
   no longer work.

   See also bbcount.