adopt it to other people that can take care of it.
The worst solution ever!

dude, dont want to sound offensive but seriously wth is your problem? u said ur terrapin has grown tooooooo big and now u want another tortoise/turtle? why not just keep the terrapin because as far as I know, most tortoise/turtles grow big too so your point it?

and besides, you seem like you lack knowledge on keeping these amazing creatures so my advice to u, read up before making more irresponsible decisions.

and just so u know, releasing a tortoise/terrapin into the wild is a bad idea. although just a single terrapin, it hurts the ecosystem, even by just a lil.