There are a few fail-safes built into Music 1. You can’t delete a Category that has even one song care in it. An Artist name can’t be removed if the name is on any song card. And a Format Clock can’t be deleted if it is clicked into even one hour-slot on a Dayformat. If you go to delete a clock and M1 says it’s can’t because the clock is on a Dayformat, it will also tell you which Dayformat(s) have the clock. Here’s what to do: