You can stop using Melacare whenever you want, it is a healthy choice to make as skin products that affect pigmentation like Melacare are often very bad for the long term health of the dermis.
Some people have reported blemishes or darkening of the skin after withdrawing from Melacare use. You can consult with a doctor to treat these symptoms in an appropriate way.
I would also suggest trying to improve your confidence and belief in being proud of your skin color.
Using skin whitening products suggests you can't be happy with the color God created you in. This is a sad state of affairs.