You can't make it go away for good because it's a genetical illness. You can
try to reduce stress. Stress will make it worse.
try to find a diet that will reduce the symptoms. (I know someone who gets psoriasis symptoms after drinking lots of milk or eating milk products. Maybe there is something you can refrain from eating to reduce symptoms.)
get cortisone ointment from your doctor to reduce symptoms.
never, ever scratch.
Visit your local doctors, they can supply you with various medications to help such as creams and oils
There's a bunch of different ways to get rid of Psoriasis: http://funadvice.com/r/bh4q7asrohj