Suede is a type of unfinished leather that can be difficult to clean because it is sensitive to water and other liquid cleaning solutions. You can remove certain stains with dry cleaning methods. Burn marks can be impossible to remove if you left an iron or another hot implement on the couch for a long time. However, if you removed the item before it burnt too far into the couch, you may be able to remove the mark or at least to make it less noticeable.
Rub an eraser over the burn mark on the couch. This will remove some of the black or brown soot associated with the suede burn.
Rub a piece of fine sandpaper over the burn mark on the couch. This will remove the top few layers of the suede and help to remove the burn mark. Work until the stain is gone or less noticeable but don't rub too hard as it could bore a hole in the suede couch.
Brush the suede with a suede brush to restore the nap on the couch.