Feel better while cleaning
Start the process by surveying the room, you have 4 walls 4 corners, and a door, do not worry about the closet yet, till the room is clean.
The first thing is to clean behind the door so it can open completely, then get about four trash bags or boxes to separate all the little stuff, and for the trash/trash. In a room where the hoarder lives, the only thing clean will be the trash can. Everything lands on the floor. They will not pick anything up, there is no care factor, no heart. So you as a parent or guardian will have to…