It the old days when providers still branded the actual phone, we would use sugar cubes to take logos off without scratching underneath. Depending on the paint tho it may be a piece of pie or a mission from hell, but usually worked amazingly (in terms of leaving base unharmed).
So much this, in NYC (less available now since Covid), there are dump sites for all this stuff (Batteries, Paint, Heavy Metals) as long as its personal amounts (ie cant come with a dump truck) it is at no cost. If you are a business and can not handle disposal fees, well you are unsustainable and should not exist.