Skin picking can be seen as a form of self harm because you are harming yourself at least some when you're picking your skin.
But it's not as bad as the self harm when you cut yourself to feel pain and bleed which can be more dangerous and bad for your body and health.
Skin picking is not really known medically as self harm but instead there's another name for skin picking which is Dermatillomania.
Dermatillomania is also known as excoriation disorder and skin-picking disorder which is a psychological condition that manifests as repetitive, compulsive skin picking.