@Edward611 You will want to have that policy I linked to in front of you and be ready to go into why it fits the parameters. Don't assume whoever you're talking to has ever seen it. Be clear, direct and make it as simple for them to say 'yes' as possible.
I would also send them a message via the platform where you can basically lay out your case.
My listing does not allow parties or extra guests [screenshot rules]
X had a party at my listing. Here is the evidence YYY.
Due to the party, the reservation was cancelled w/no penalty by Airbnb on Y date.
The guests review meets the criteria set out by Airbnb for removal of party reviews. Link and paste the wording.
Something along those lines and then you can call and follow up and they can see the link and policy. It may take a few reps and a lot of your time, but I would think you have a decent shot at getting the review removed.