Pages 81-82 in the Legacy manual discuss options available in the menus you cycle through: Here are screen shots of those pages, on pp82 at the bottom an option to clear the database is shown. Hope this helps.
You can also connect it to a PC and use the LEGACY SYSTEM UTILITY VERSION 2.0 to do the job. The LSU is also very handy for entering data into the command base, you can do it with a full keyboard and not with a knob and buttons.
Here's the LEGACY SYSTEM UTILITY MANUAL v2.0 that shows you how to use it. I have mine connected through my network, so I can maintain the command base from my computer without doing any cabling.
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