Learn Hardcore Italian: Togli la spina del computer prima di pulire.

Because it’s a direct command in the informal singular. Togli is the second-person singular imperative of togliere. Use it when speaking to one person you address as tu.

How do I say this to more than one person, or formally?

Plural informal (you all): Togliete la spina del computer prima di pulire.
Singular formal (to one person you address as Lei): Tolga la spina del computer prima di pulire.
Plural formal: Tolgano la spina del computer prima di pulire. (rare outside very formal contexts)

How do I make the command negative?

Informal singular (tu): Non togliere la spina... (negative imperative uses the infinitive for tu)
Plural informal (voi): Non togliete la spina...
Singular formal (Lei): Non tolga la spina... With pronouns, both are common for tu: Non toglierla / Non la togliere.

Can I replace la spina with a pronoun?

Yes. La spina is feminine singular, so:

Positive command (enclitic): Toglila prima di pulire.
Negative command: Non toglierla or Non la togliere. If you specify you’re cleaning the computer, you can also say: ...prima di pulirlo (attach -lo to pulire).

What’s the difference between spina and presa?

Spina = the plug (the male piece on the cable).
Presa (di corrente) = the wall socket/outlet (the female receptacle). So you can say: Stacca la spina dalla presa.

Why is it la spina del computer and not something with da?

Del = di + il and marks possession/association: la spina del computer = the computer’s plug. Da would indicate movement/from a place (e.g., dalla presa = from the socket), not the item’s owner.

Is togliere la spina the most natural verb here?

Very common alternatives (often even more idiomatic) are:

Stacca la spina (del computer).
Scollega il computer dalla presa.
More formal/technical: Disinserisci la spina. Staccare and scollegare emphasize disconnecting; togliere emphasizes physically removing.

Does staccare la spina have an idiomatic meaning?

Yes. Beyond the literal “unplug,” staccare la spina also means “to take a break, switch off (mentally).” In your sentence, the meaning is literal because of the context (del computer).

Should it be prima di pulire il computer to be clearer?

You can say:

...prima di pulire il computer (explicit object), or
...prima di pulirlo (attach the pronoun), if “it” clearly refers to the computer. Prima di pulire alone can be understood from context but is less explicit.

Why is it prima di + infinitive and not prima che?

Use prima di + infinitive when the subject of both actions is the same (here, “you” both unplug and clean). Use prima che + subjunctive when the subjects differ: Togli la spina prima che qualcuno pulisca.

How is pulire conjugated? Is it an -isc- verb?

Yes. Present tense: pulisco, pulisci, pulisce, puliamo, pulite, puliscono. After di, you must use the infinitive: prima di pulire (or pulirlo with a pronoun).

How do I pronounce togli and the gli sound?

Togli is roughly “TOH-lyee.” The gli represents a palatal sound [ʎ], like the “lli” in the Spanish “paella” for many English speakers. Keep the g silent; it modifies the l sound.

Is computer masculine? How do I form the plural?

Yes, computer is masculine invariable:

Singular: il computer
Plural: i computer (no change in the noun)

Can I move the time clause to the front?

Yes: Prima di pulire, togli la spina del computer. This is very natural in Italian.

Where can I put politeness markers?

Common options:

Per favore, togli la spina...
Togli la spina, per favore.
Formal: Per cortesia, tolga la spina... or La prego, stacchi la spina... You can also soften with a conditional: Potresti togliere la spina...?

Is there any risk of saying toglia instead of tolga?

Yes—avoid toglia. The correct formal imperative is tolga (from togliere). The past participle is irregular too: ho tolto (not “togliuto”).

Why is the article la used before spina?

Italian uses definite articles more broadly than English, especially for known/specific items. Here, the plug is specific (the computer’s plug), so la spina sounds natural.