Returning Equipment Before Cancelling Internet Plan

Hello,

I was wondering if it were possible to return my internet equipment, like my router, before officially cancelling my plan? Additionally, can I do this without knowing the account number or any account information?

My ex-roommate and I are parting ways. My roommate is already living in another state, but they are in charge of our Xfinity account. For personal reasons, I want to avoid as much contact with them as possible for my own safety. My ex-roommate will supposedly cancel the internet some time this month, but I don't know when. I am left with the router/modem and I am hoping to be able to turn it in, even if it's before our service ends. Can I drop my router off at an Xfinity store or UPS store to have it returned, even if our plan hasn't ended yet?

Thank you so much for any and all help.