I contacted a sitter (sitter to sitter). Now how do I delete that message from my Rover mailbox?

I wanted to get to know the sitters in the area because I needed to refer a client to someone else. On this Q&A board, it said the only way to contact them is by creating a "stay request" and message them from there. I did that, but now I can't get the messages out of my mailbox, even though the requests have expired. I can't archive them, nor delete them. Anyone know how I can?