I’m trying to reset my apple 8 watch but when I go to general to hit reset it won’t allow me to hit the reset button

Try a forced restart first.

i.e. press and hold both the side button and Digital Crown for at least 10 seconds, then release both buttons when you see the Apple logo. Then try again.

If that does not help try this

Put your watch on its charger and keep it there until you complete one of these steps. (select the watch OS version)

Erase Apple Watch – Apple Support (UK)

If you want to sell it on you also need to remove Activation lock by removing t from ypour account at https://icloud.com/find

To unpair and erase watch and remove Activation Lock

From a web browser,sign in to iCloud.com with your Apple ID.

Go to Find iPhone.

Click All Devices at the top of the screen.

Click your Apple Watch.

Click Erase [device]. Select Next until the device is erased.

Click Remove from Account.