You should check Ontario laws on squirrels. My understanding is as follows (please double confirm yourself):
1. You can trap the squirrels but you can't transport it to another place.
2. To prevent the squirrel from returning, you have to drive to farther than 10 kilometers.
It is probably legal to trap and kill but you need to double check. A feasible way is to contact pest control. Tell them you will trap the squirrel yourself but ask them to handle the trapped squirrels.
It may cost you but this is probably the best way ... before they get into your roof ...