Second hand beats show they’re still connected to another device?

There was a pair of beats wireless 3’s in my new house when I moved in, left behind by previous owners. After charging for 3 days, they surprisingly turned on!

Well, the 5 lights that show the battery level are on, but the one light on the other side that’s supposed to be on when ready to pair isn’t… Google tells me that if the light is off, it’s already paired to a device. I’m assuming it’s the previous owner’s phone. How do I unpair it?