Trying to log out iCloud forgot the password

I let my friend borrow my phone and she forgot about the password on her iCloud and I have been trying to log out but it doesn’t let me and I keep on asking her but she keeps on saying that she forgot it so I need help to log out of my iCloud Because my other phone broke and it doesn’t let me get messages or anything but this one works but the problem is I’m trying to put my Sim card in but I need to log out of the iCloud And by any chance, can you restart my phone? It’s a iPhone 8