@Erin5795 Be aware that an Inquiry message only requires a response, you shouldn't click on decline for an inquiry, as declines count against you. ( Requests do need to be either accepted or declined within 24 hrs unless you can get a guest to withdraw it if it is inappropriate).
I would simply send a message back saying "I don't deal off- platform" and click on the report button next to the message, then check the appropriate box.
Also, you should go back and edit the description part of your listing, filling out all the available fields, like "The Space", "Guest Access", "Other things to note". Your description is quite incomplete and short on information.
You are going to have to be vigilant when vetting guests, as your place looks like a party magnet and has a high guest count, and scammers and partiers often target new listings, assuming the host is naive.