Hi Taleh,
You can start by checking your house rules to ensure they clearly state the maximum occupancy limit and any policies regarding additional guests. Next, message the guest through Airbnb's platform to address the situation politely but firmly. Mention that your listing allows a maximum of four guests and that any additional guests require prior approval.
Request clarification on the situation and remind them of your house rules. If the guest doesn't respond or comply, you can escalate the issue by contacting Airbnb support to report the violation.
Ensure you have evidence, such as the doorbell footage, to support your claim. Keep all communication professional and within the Airbnb platform to maintain a record of your interactions.
I hope this helps.
All the best,
Upfish Management