I know that I can delete an IP phone via the station with 90-23-01, however a cable tech pulled the phone to take to a different location. Is there a way to delete it via the switch?

You can enter programming another on the system and do the 90-23-01, key in the extension number of the extension to remove then press 1 then transfer.

even if that station is no longer on the system?

It still exists in programming.