What is the best way to break the rivets that hold the window motor to the door?

Hello,

In order to get those rivets out, you will have to drill them.

All you want to do is to use a drill bit slightly smaller than the rivets and drill. This will break the rivets and loosen the window motor regulator.

https://www.2carpros.com/articles/how-to-check-and-replace-a-electric-power-window-motor

I have attached the replacement procedure below for your reference.

Please let me know if you have any questions.
Thank you.