Nose hairs are important to your nose but the nose hairs do not help you smell.
You can still remove all your nose hairs and still be able to smell properly even without the nose hairs.
The nose hairs do serve an important function such as helping your nostrils retain moisture and the nose hairs also keeps particles from entering your body, reducing allergies and infections.
So it's best to leave your nose hairs in your nose and not remove them.
However if you do prefer to remove the nose hairs then you can still survive without them.
I used to pluck my nose hairs and I was still able to smell just fine without the nose hairs.
But now I just trim the nose hairs so that part of the nose hairs are still in my nose while I remove part of them.
Trimming nose hairs with a nose hair trimmer is much safer than plucking the nose hairs.