The leave utility waits until the specified time, then reminds you that you
have to leave.  You are reminded 5 minutes and 1 minute before the actual
time, at the time, and every minute thereafter.  When you log off, leave 
exits just before it would have printed the next message.

To get rid of leave you should either log off or use `kill -s KILL` giving its
process id.

This program is included with FreeBSD and is distributed under the BSD license.