Não quero destruir nada.

In Portuguese, the subject pronoun is often omitted when the verb form already makes the subject clear.

Here, quero means I want, so eu is not necessary.

• (Eu) quero = I want
• (Você) quer = you want
• (Ele/ela) quer = he/she wants

So Não quero destruir nada is completely natural. You could say Eu não quero destruir nada, but the eu is usually only added for emphasis, contrast, or clarity.

In Portuguese, não normally goes directly before the verb it negates.

So:

• quero = I want
• não quero = I do not want / I don't want

This is the standard position for negation in simple sentences.

Examples:

• Não sei. = I don’t know.
• Não posso. = I can’t.
• Não quero sair. = I don’t want to go out.

Because after querer (to want), Portuguese usually uses an infinitive verb, just like English often does.

• quero destruir = I want to destroy
• quero comer = I want to eat
• quero sair = I want to leave

Only the first verb is conjugated:

• quero = conjugated
• destruir = infinitive

So Não quero destruir nada follows a very common pattern: não + querer + infinitive + object

Destruir is the infinitive form of the verb meaning to destroy.

In this sentence, it comes after quero, so it works like to destroy in English:

• quero destruir = want to destroy

It is an -ir verb, although its forms can look a little unusual in some conjugations because of the u/i sequence.

For example:

• eu destruo = I destroy
• você destrói = you destroy
• nós destruímos = we destroy

But in your sentence, you only need the infinitive: destruir.

Nada means nothing or anything, depending on the sentence structure.

In a negative sentence like this, não ... nada works like not ... anything in English:

• Não quero destruir nada = I don’t want to destroy anything

Portuguese often uses this kind of negative structure naturally:

• Não vi nada. = I didn’t see anything.
• Não disse nada. = I didn’t say anything.

So nada comes after the infinitive because it is the object of destruir:

• destroy what?
• nada

Yes, in a way it is, and yes, it is normal.

Portuguese commonly uses multiple negative words in the same sentence, unlike standard English.

Examples:

• Não vi nada. = literally I didn’t see nothing, but naturally I didn’t see anything
• Não conheço ninguém. = I don’t know anyone
• Não vou a lugar nenhum. = I’m not going anywhere

So não + nada is completely correct in Portuguese.

Grammatically, that is unusual and not the normal way to say it.

The natural sentence is:

• Não quero destruir nada.

Putting não before quero negates the whole idea of wanting:

• I do not want to destroy anything

Quero não destruir nada sounds awkward because it tries to place the negation inside the infinitive phrase in a way that Portuguese usually avoids in everyday speech.

So for a learner, the safe and natural choice is:

• Não quero + infinitive

Yes, you could. Coisa nenhuma also means nothing / anything at all in negative contexts.

So these are both possible:

• Não quero destruir nada.
• Não quero destruir coisa nenhuma.

The version with nada is shorter and very common.
The version with coisa nenhuma can sound a bit more emphatic, depending on tone and context.

Não is usually pronounced roughly like nowng or nãw, but not exactly like any one English word.

Important points:

• The ão sound is nasal.
• Your mouth does not fully close into a clear n sound at the end.
• It should not sound like nao with two separate vowels.

A rough learner-friendly approximation is:

• now with nasal resonance

But try to listen closely to native pronunciation, because nasal vowels are a very important feature of Portuguese.

In Brazilian Portuguese, destruir is roughly pronounced like:

des-troo-EER

A few notes:

• The stress falls on the last syllable: -ir
• The u and i are both pronounced; it is not a single English-style vowel
• The final r in Brazilian Portuguese is often pronounced with a breathy h-like sound, especially in many accents

So depending on the accent, the end may sound a bit like:

• des-troo-EER
• or des-troo-EEh

It is neutral and natural in both spoken and written Brazilian Portuguese.

There is nothing especially formal or informal about it. It could fit many situations:

• casual conversation
• a serious discussion
• writing dialogue
• ordinary statements

If you add eu at the beginning, it may sound slightly more emphatic, but not more formal:

• Eu não quero destruir nada.

Quero is the present indicative form of querer.

Specifically:

• eu quero = I want

In this sentence, it expresses a present desire or intention:

• I don’t want to destroy anything

Even though it is present tense, like in English, it can also refer to what the speaker feels right now about a future action.

Yes, depending on the sentence.

By itself or in a clearly negative sense, it usually means nothing:

• Nada aconteceu. = Nothing happened.

After não, it often corresponds to English anything:

• Não quero nada. = I don’t want anything
• Não vi nada. = I didn’t see anything

So in your sentence, although nada literally relates to nothing, the most natural English meaning is anything.

No, that is not correct for standard Portuguese.

If you use nada in this kind of sentence, you normally need the negative marker não:

• Não quero destruir nada. = correct
• Eu quero destruir nada. = not correct in standard usage

Without não, the sentence clashes grammatically because nada usually needs that negative environment here.

If you want a positive sentence, you would say something like:

• Quero destruir tudo. = I want to destroy everything
• Quero destruir alguma coisa. = I want to destroy something

The structure is:

não + [conjugated verb] + [infinitive] + object

In this sentence:

• não = negation
• quero = conjugated verb (I want)
• destruir = infinitive (to destroy)
• nada = object (anything / nothing)

So the pattern is very useful for many other sentences:

• Não quero comer nada. = I don’t want to eat anything
• Não posso fazer isso. = I can’t do that
• Não vou dizer nada. = I’m not going to say anything