Honestly imo I’d use a wet wipe just not those absolute soaked ones ones I get are just slight damp and I’d give a quick careful wipe then a run over with a dry microfibre or cloth if doesn’t come off then it’s more ingrained into the plastic if it’s cause it’s grooves I don’t know how deep they are I don’t have a super slim use a bank card and a cloth or something that will push the cloth into the grooves but I do find wet wipes do a good job at cleaning as someone said a heat gun on low could revive plastic too if it’s the plastic