Pairing old watch with new phone

I neglected to unpair my watch from my old phone before disposing of it. Now I can’t pair with new phone. App on my phone only shows pairing screen but won’t pair. I can’t do anything with my phone on the app. Strangely the new phone model shows up on my watch in device info but it displays both the old and the new phone models? And I am receiving emails etc on my watch but that may be because it’s also paired with my older laptop.