iPhone 7plus is disabled connect to itunes

When I turn on the phone it reads Iphone disabled connect to itunes. I was wondering if there was a way to reset this phone completely to be able to use it again? It was my dads iPhone who recently passed away and I was hoping to give it to his grandson to use. I don't know his password or user name. He switched to Android a couple years ago. Can this phone be used again or do I have to recycle it? Thanks