Can we use a cotton swab (Q-tip) to clean our ears?

Cotton swabs are okay to clean your outer ears but not inside your ear canal.
Using a cotton swab to clean your inner ears poses risks such as puncturing the eardrum and pushing wax further in, which can cause infection.

Do we really have to clean our ears?

Yes, clean your outer ear with soap, water and a washcloth while you shower.
No, do not clean your inner ear.
The skin in your ear canal naturally grows in an outward, spiral pattern. So, as the skin sloughs off, the ear wax goes with it. Most of the time the ear wax will loosen and fall out on its own while you are asleep.