Choose the passive voice of the sentence.
Shut the door.

In Active Voice, a sentence emphasizes the subject, performing an action.
In Passive Voice, a sentence emphasizes the action or the object of the sentence.
The given sentence is an imperative sentence in the active voice.
An imperative sentence in the passive voice has the following form: Let + object (door) + be + past participle (shut).
Hence, the correct passive voice is Let the door be shut.