i cant reset mu apple watch series 3. i have entered wrong passcode too many time. what shoul i do?

Hi

Follow these steps to erase your locked Apple Watch and re-pair it with your iPhone:

• Connect your watch to its charging cable, connected to power.
• Whilst keeping your Apple Watch on the charger:
  • Press and hold the side button until you see the Power Off slider.
  • Press firmly on Power Off (do not try to slide it - just press down more firmly than a normal tap), release your finger, tap on Erase all content and settings and confirm when prompted.
• Re-pair your Apple Watch using the Watch app on your iPhone, choosing to Restore from Backup if offered the option.

More information:

Set up your Apple Watch - Apple Support

If you forgot your Apple Watch passcode - Apple Support