There's your problem then. Don't use "brushes" or dodge or burn tools or spray can or anything that applies more than one color of pixel. If you're not in control of which color pixel goes where, then it's not pixel art. Check out the tutorial for more info.

I made it on paint brush and what do you mean by un needed colors! Thanks! for comment. 

You could cut some unneeded colors and make the BG transparent, but otherwise it's a good start.