How do I transfer my $25.00 promo code to money I can transfer into my checking account?

I am pretty certain you cannot take the credit from your account the promo is to be used toward your first booking on Rover. I'd call Rover Support to be sure though @ [Edit: Rover’s contact options have changed. Visit the Rover Help Center at https://support.rover.com/ to find the phone number, help articles, or chat with the team]

You can not. You have to use it.