Reset iphone 10 with unresponsive screen

I dropped my iphone 10 and shattered the screen. I replaced it with a new iphone 12 pro and loaded the 12 from my cloud backup. I now want to reset the old phone so I can turn it in for refurbishing without concern about any of my data still being on the phone. All the references of how to accomplish this include unlocking the old phone which I cannot do because the screen is non responsive.

Advice on how to get this done appreciated.