Good advice above. Six weeks of deca probably did not do very much damage. As someone else mentioned, it is suppressive of natural test production and it does have a long half life (15 days). In 7 half lives (105 days=3.5 months), 99.2% of the deca will be out of your system. The decanoate metabolites can be detected (doping tests) for up to 18 months.
You should wait at least until you are in your 20's before taking steroids. Taking them too young could result in stunted growth and other problems. Just eat like it's going out of style, train hard (without overtraining), and get a lot of rest and you will grow just fine without steroids.
Spidey is a fictional character. I do not use or condone the use of illegal drugs. Any references to steroids or other illegal drugs is purely for entertainment purposes and role-playing.