My ex is in my account

So I noticed the day we broke up my ex’s phone was making the motion detected sound when he was walking past the doorbell each time and at first I thought it was my phone until I saw it across the living room. I changed my password and disconnected all mobile/computer devices that said they were logged onto my ring account yesterday and then tonight he sent me a video and I heard his phone doing the same sound again. I know he doesn’t have a ring system so how can I disconnect him from being in my account and spying on me? I don’t know if he cloned my phone or what but it’s obvious he’s in my ring account somehow and seeing all my cameras views.