Just unlink the account, and put your login in.
I'm pretty sure this is a Spotify issue where the app on a phone is able to see any connected devices. I use it to play music around my house in different rooms so that same feature can be abused in a network situation like a dorm.
Edit: those saying to turn it down with PS button and L1, the Spotify app let's you control volume of the device it's being played to.