Neem die komitee af deur die driepoot te gebruik.

Because the dictionary verb is afneem, which is a separable verb in Afrikaans.

In a main clause or command, the verb splits:

• Neem die komitee af.

But in other structures, it may stay together or split around te:

• Jy moet die komitee afneem.
• om die komitee af te neem

So neem ... af is the normal command form of afneem.

Afneem has several meanings in Afrikaans, so context matters a lot. It can mean things like:

• remove / take down
• record / film / photograph
• decrease
• administer (for example, an exam)

Because the sentence includes die driepoot (the tripod), the most likely meaning here is something like photographing or filming the committee.

After deur when Afrikaans expresses a method or means, it commonly uses te + infinitive.

So:

• deur die driepoot te gebruik = by using the tripod

This is a very common pattern:

• deur hard te werk = by working hard
• deur te oefen = by practising

It means by using ... or through using ....

In this sentence:

• deur die driepoot te gebruik = by using the tripod

It explains how the action is done. So it is giving the method.

Because die is the definite article the, and each noun needs its own article here:

• die komitee = the committee
• die driepoot = the tripod

Afrikaans does not change the for gender, and it also uses die for both singular and plural definite nouns.

It is singular here.

• die komitee = the committee
• die komitees = the committees

Even though a committee is made up of several people, the noun itself is grammatically singular, just like in English.

It literally breaks down as:

• drie = three
• poot = leg / foot / paw

So driepoot is literally something like three-leg, which is the Afrikaans word for tripod.

This is a good example of how Afrikaans often forms nouns by combining smaller words into compounds.

In Afrikaans, the imperative is often just the basic verb form.

So:

• Neem! = Take!

That is why the sentence starts with Neem. It is giving an instruction or command.

If you want to sound more polite, you can add asseblief:

• Neem die komitee asseblief af deur die driepoot te gebruik.

With a separable verb in a main clause or command, Afrikaans usually places:

• the finite verb first
• then the object
• then the particle

So the normal order is:

• Neem
  • die komitee
    • af

That is why Neem af die komitee sounds wrong.

Yes, often you could.

• Neem die komitee met die driepoot af.
  = Photograph/film the committee with the tripod.

This is shorter and often more natural in everyday speech.

• deur die driepoot te gebruik is more explicit and emphasizes the method: by using the tripod.

So both are possible, but they have slightly different emphasis.