If you can stop the service and start again do these steps.

I didn't saw your last question: if you can delete them from windows explorer? yes, you can but first, you have to make sure that when you go to tempdb>Properties>files in the size column they dont have the same size, if they do, when you stop the service, remove the files and start again SQL server will automatically recreate them using the same space and have the same size.

Regards!