It is common for your pet to have a predilection for biting your shoes, clothes or furniture. Dogs love to chew and chew things up, but do not understand, unless you explain to them very patiently, what they can and cannot chew.
When you see them biting something they shouldn’t, say “no” or “eh” in a clear and firm tone that leaves no doubt that it is an improper action. Chances are you won’t get it right the first time. His learning is based on associations, so you will have to repeat it to him several times in order for him to establish the relationship.
Instead of slapping him on the butt or losing your temper, it is preferable that you give him a toy that he can chew on. Don’t use old clothes or something similar because then you are implying that he can chew on your clothes or other household objects. Give him his own toy. There are objects designed for them, such as edible slippers, bones to gnaw on or non-toxic plastic dolls.
It really pays you much more to be patient and tenacious with this technique than to scare the dog with shouts or sticks. I know you do not intend to hurt him, but to teach him, but the method of hitting is not very effective and, in addition, it can cause your dog to develop aggressive instincts.