For the next two weeks, whatever you wear, wash dry and put somewhere other than your room. Never put anything you wear in the next fortnight back into your room.
At the end of the fortnight, bag up every single bit of clothing/shoes etc into bin bags.
If you have the patience, bag in categories - shoes, underwear&socks, tops, bottoms, dresses, outerwear.
If you have a loft, shove all these bags in the loft.
Clean the wardrobe/drawers and put the stuff you always wear (which wasn't in the bedroom) away.
Enjoy the space.
In time, grab a binbag from the loft - just one at a time - and sort through it. Do it with a movie on or a box set. Be ruthless and ask yourself - will I need this in the next couple of months? If yes - keep; if not, bin.