Verruca on foot | Lemon Oil | Wart Treatment

My son has a verruca wart on his left foot.
It's right on the sole of the foot and hurts him when he walks. He is four years old.

I looked at pictures online and I think it's a verruca wart.

What's the best treatment for this?
Should I buy one of those ointments from a drugstore? What about freezing spray treatments for warts - will that be OK if he is only four years old?

My sister said that using lemon oil like they use for aromatherapy will be a good idea but I don't want to burn his skin with it.

I'd be grateful for advice - thanks

Val