How to Factory Reset Apple Watch without an iPhone?

I traded in my phone for the 15 pro today. I have been using a Series 3 Apple Watch, and didn't realize it wasn't compatible with my new phone until the old one was traded in. Now I can't figure out how to factory reset it to either attempt to pair it one last time or sell it. Everything I find says to unpair from my phone, which I can't do as I don't have it anymore. Is there any way to just do a hard reset on the watch itself? I tried the reset option available on the watch, but it keeps telling me I've used the wrong password (I haven't)

[Re-Titled by Moderator]