I removed an Apple Watch 2 from my phone while trying to UNpair it.

Hello Laurie_Belle,

If you forgot the Apple Watch passcode, follow the steps below to reset it:

1. "Put your watch on its charger and keep it there until you complete these steps.
2. Press and hold the side button until you see the power button in the upper-right corner of the display.
3. Press and hold the Digital Crown until you see Erase all content and settings.
4. Tap Reset, then tap Reset again to confirm.
5. Wait for the process to finish, then set up your Apple Watch again. When asked, restore from a backup.

"

If you forgot your Apple Watch passcode - Apple Support

Hope this helps.

Cheers.