How can I remove the scar I have from using garlic to remove a mole?

It is difficult to give you helpful advice without seeing the scar. I’m not sure whether you mean a scar, as in , the area blistered or the surface was damaged, or whether you mean the pigment has become darker there. If the former, you probably ought to ask a nurse or GP to have a look at it. If it has left dark pigmentation, but not actual inflammation, then Kojic acid at 2% should be comfortable and effective, over a few months. Otherwise, liquorice extract can lighten skin areas with excessive melanin. I wouldn’t use anything stronger as you seem to be saying this is a site of a mole, it is very important that you don’t irritate the skin there. Before you treat any cosmetic features on the skin, you should make sure it isn’t inflamed or damaged or you could make the area much worse. Please don’t try to bleach it with anything acidic (like lemon juice!) this can cause very unpleasant burns. I hope it settles down.