i got a iphone off ebay and the phone is iphone finder on and the owner doesnt know the passwords what do i do

Return it and get your money back. If it was not disclosed in the auction that it is activation locked, and the seller refuses to give you a refund, file a claim with eBay. It's useless unless the owner of the account used to lock it removes the lock. There is no way to bypass the activation lock.

You can always use it as a rectangular frisbee.