If it has Onstar delete, look at the parts label in the glove box, on the door or on the spare tire cover, where ever they happen to put it on that model I don’t know. There are option codes that the vehicle was built with, the option code for the delete is ‘UEO’.
Did you buy a used vehicle? Typically fleet vehicles are special ordered for specific fleet customers and not sold NEW to general public. Could be its a short term lease return like from a rental company like Enterprise etc. I know the local rental company at airport was selling used cars a few years ago, Impala’s. So we called and asked if any were still available and she told us we were too late, if they were not sold be a certain date they had to be returned to Chevrolet as a condition of the lease. So the rental company could flip them for a profit or let them go back to GM. They were like 1 yr old with low miles.