If the upper lip hair is thick enough no amount of shaving will do, the skin just seems to bulge out with the black bulbs just beneath the skin. I had such a dense moustache at 16 even though I had no beard at all at that age!!
If its thick, no amount of shaving and makeup will truly hide it satisfactorally.
I used to pluck it out, but you have to have an insane patience to do that.
Electrolysis is the way to go (or laser, but I've never used it since I did electro in 1993 before laser).