Remove the ear cups from your headphones, if possible. Then, using a microfibre cloth, wipe any grime or dirt from the ear cups and the rest of the unit. Get another clean cloth and put a bit of rubbing alcohol in it. Use this to clean the surface of your ear cups and the rest of the headphones. Using a cotton swab with rubbing alcohol, remove grime and dirt from the headphones' nooks and crannies.