@Tata38 You will need to contact Airbnb customer service to deal with this (which isn't easy right now, as they are swamped with COVID cancellation calls and mesages) . This is just a discussion forum for hosts and guests.
If these scam messages you are getting are coming in the form of Inquiries, rather than Booking Requests, you don't need to decline them- just report, and send back a message to the scammer saying "No". Simply replying to an Inquiry message is all that's required- you don't need to click on pre-approve or decline, and you won't be penalized.