Hi
If you have removed the passes from your iPhone, but they remain on your Apple Watch, then the following steps may help:
If you have not yet done so, update your iPhone and Apple Watch to the latest compatible software versions, starting with your iPhone:
Restart both your iPhone and your Apple Watch, turning both off together and then restarting your iPhone first:
If the issue persists, then it may help to unpair and re-pair your Apple Watch:
If the issue still persists, then I suggest that you contact Apple Support (remote diagnostics may be available, if required), make a Genius Bar reservation or visit an Apple Authorised Service Provider for assistance: