Formal:
* أغلق هذا الباب. (ighliq hadha al-bab) - This is the most literal and formal way to say it.
* أرجو منك إغلاق هذا الباب. (arju minnak ighlaaq hadha al-bab) - This translates to "I ask you to close this door." It's more polite than the previous option.
Informal:
* سِكّر الباب. (sikir al-bab) - This is a more informal and casual way to say "close the door."
* قفل الباب. (qifl al-bab) - This literally means "lock the door," but it can also be used to mean "close the door" in informal contexts.
Note: The most appropriate way to say it will depend on who you are talking to and the situation.