@Christina989 - as @Anonymous has indicated.
If you DO use instant book, what I've found works rather well (though not every time):
I have a blurb in my house rules that states that 3rd party bookings are in contravention to Airbnb's Terms of Service (Section 14), I then say that we don't accept them.
In my "pre-approval" message (under booking settings/guest requirements), I've written the following:
" **Note: reservations made on behalf of someone else violate Airbnb's terms of service. Please do not continue if you will not personally be staying."
Since doing this, I've only had one person try it on. It was someone who didn't meet all of my IB requirements, so he was trying to request a place for some of his work crew. Maybe he thought it didn't apply to him. He was very upfront about who would be staying, if I accepted the booking. I declined, and directed him to the "Airbnb for Work" link.
I haven't had anyone instant book since putting the text in the pre-approval message, but it has happened. I simply let the booker know that it violated the terms of service, and that they would need to cancel. Obvs, I let them know that I'd be happy to host whomever...they just needed to book with their own account.