Dobbiamo evacuare l'ufficio.

Dobbiamo is the present tense, first-person plural form of dovere.

• dovere = to have to / must
• dobbiamo = we have to / we must

So the subject is we.

Because after the modal verb dovere, Italian normally uses an infinitive.

Pattern:

• dovere + infinitive
• potere + infinitive
• volere + infinitive

So:

• dobbiamo evacuare = we must evacuate

You do not add di here.
So dobbiamo evacuare is correct, not dobbiamo di evacuare.

It can mean either, depending on context.

• Dobbiamo evacuare l'ufficio.
  = We must evacuate the office.
• It could also be understood as We have to evacuate the office.

In many everyday situations, Italian dovere covers both ideas, and English chooses between must and have to based on style and nuance.

Because ufficio begins with a vowel, and the masculine singular article il becomes l' before a vowel.

So:

• il libro
• il tavolo
• but l'ufficio

This is called elision.

Ufficio is masculine.

• singular: l'ufficio
• plural: gli uffici

So if you wanted to say the offices, you would say gli uffici.

Because l'ufficio is the direct object of evacuare.

In this sentence:

• Noi (understood) = subject
• dobbiamo = verb
• evacuare = infinitive verb
• l'ufficio = the thing being evacuated

Italian, like English, does not use a preposition before a direct object here.

Yes, that is grammatically correct.

Italian often drops subject pronouns when they are already clear from the verb ending.

So both are correct:

• Dobbiamo evacuare l'ufficio.
• Noi dobbiamo evacuare l'ufficio.

The version with noi sounds more emphatic, as if you want to stress we.

No, evacuare ufficio is not correct here.

Italian usually needs an article before a noun like ufficio when talking about a specific office.

So:

• evacuare l'ufficio = evacuate the office

The article shows that the speaker has a particular office in mind, or that the office is understood from context.

A rough pronunciation is:

dohb-BYAH-mo eh-vah-KWAH-reh loo-FEE-choh

A few helpful points:

• dobbiamo has stress on -bbià-
• evacuare has stress on -à-
• ufficio has stress on -fì-
• ci in ufficio sounds like ch in church

Also notice that the bb in dobbiamo is a double consonant, so it is held a little longer than a single b.

For the negative, put non before the conjugated verb:

• Non dobbiamo evacuare l'ufficio.
  = We must not / do not have to evacuate the office
  (The exact English meaning depends on context, so be careful.)

For a question, Italian often keeps the same word order and changes the intonation:

• Dobbiamo evacuare l'ufficio?
  = Do we have to evacuate the office?

Yes, evacuare is a normal and natural verb, especially in an emergency or safety context.

It is often used when people must leave a building, room, or area.

A related verb is sgomberare, which can mean to clear out or empty, but it is not always exactly the same. In many emergency situations, evacuare is the clearest choice.