What I've done in the past is run a system notes saved search and see what records are being created/edited via csv context and by whom. Then go check with those people about what import templates they're using and whether others can be cleared out. The more simple, but slower, solution involves pulling access, waiting 1 year, and then removing all the ones no one screamed about. 😆 My understanding is that you can really only see the last time a template was modified, and there isn't a way to see when a particular template was last run, but if anyone else knows better, I'm all ears.