I think there's a little square hole in the metal tab and the plastic connector has a tab that locks into the square hole. Usually, you can get hold of the connector and wiggle it side to side and at the same time, pull up hard on the connector and it should come off the tab. It might be hard to get your hand on it because of where it's located, though.
Most 4-wheeler problems are caused by a loose nut connecting the handlebars and the seat!!
You only need two tools in life -- WD-40 and duct tape. If it doesn't move and should, use the WD-40. If it shouldn't move and does, use the duct tape.