Command - /NickServ DROP
Usage   - /NickServ DROP <nick>
This command allows the owner of a nick mark the nick as dropped (un-registered).
If the owner of the nick doesn't identify to it after a few weeks, the nick will be removed from the services' database.
Note: You must be identified to NickServ in order to use this command.
Example(s):
/NickServ DROP shiran