You can use CLR to remove the paint from vinyl siding.  However, it’s easier to use a paint remover like Goo Gone.  It will clean the paint, but not damage the siding. You must not use CLR to clean the vinyl siding. CLR is acidic in nature and will damage the vinyl siding.  Homeowners have used CLR with success to remove paint from vinyl siding. This is dangerous, as the siding might be ruined if it is not done properly.  It is thus better to hire a professional for the task.