Factory Reset

What is Factory Reset?
Factory Reset restores your Pebble to factory setting (ie. it forgets pairings and removes apps and data you have stored on Pebble). Be very careful before you use it, because once Pebble has been reset, it cannot be undone. To restore your Pebble to factory settings, select Settings from the main menu, then choose Factory Settings, which is the very last option.

When should I use Factory Reset?
You should use Factory Reset whenever you feel like starting fresh with Pebble, or if you are going to re-gift or re-sell it, so that the new owner gets a clean Pebble.

If I cannot get to Factory Reset?
If your Pebble is frozen and not letting you navigate through the menu, you will need to reboot your Pebble. This will not affect your smartwatch's firmware or pairings; it will simply force it to shut down and restart.
To reboot Pebble, simultaneously hold the back, up, and select buttons until the Pebble logo appears.
Once it restarts, you should be able to navigate to Factory Reset.

https://pebble-help-legacy.rebble.io/