Can’t find the link anywhere.

If you go to the page that shows all your pets (Personal tab>Pets), click on the drop down menu next to the pet you want to abandon. 'Abandon' will be near the bottom on the list that opens. You can go from there. The pet then goes into Adopt-R-Us, if you're curious.

Okay I just abandoned a Vivid pet called Katrina c: thank you