Was still experiencing the glitch and found that if I delete it from the web client and not the signage studio, it successfully deleted.
For security reason, stations whose Last Updated counter is higher than 43200 can be deleted. Note that the counter resets every 25hrs to 26hrs thus you have a 13hr window to delete the station.
If the condition above is met:
For Legacy Studio (Studio Pro), to delete, make sure to highlight the station, then click the Delete icon (circled-X) which marks the station for deletion. after marking all stations you want to delete, hit File | Save/Upload to permanently delete them.
For Sign Studio, click on Disconnect Player
best regards
-ADMIN