Remove files and their history from the depot
Obliterate removes files and their history from the server in a way that they won't come back. It retrieves space used by those files in the archive and then clears the files from all lists maintained by the server. Files in client workspaces are not affected, except that Perforce will no longer recognize them as being under its control.
Obliterate carefully undoes the lazy copies made when 'p4 integrate' creates a branch. Because of this, it is possible that obliterating files will not recover any space.
The -y flag instruct obliterate to do its work. Otherwise, it just displays what it would do.
'p4 obliterate' requires superuser access granted by 'p4 protect'.