By default a normal user can abort the shutdown. They could also configure group policy to prevent shutdown permissions which also prevents aborting a shutdown.
The GPO is Computer Configuration > Windows Settings > Security Settings > Local Policies > User Rights Assignment > Shut down the system.
Does that require admin access? It wasn’t their machine, it was one the school provided for the auditorium.
By default a normal user can abort the shutdown. They could also configure group policy to prevent shutdown permissions which also prevents aborting a shutdown.
The GPO is
Computer Configuration > Windows Settings > Security Settings > Local Policies > User Rights Assignment > Shut down the system.