I have an unknown skin growth on the base of my penis since 6-7years ago. It does not itch or hurt or grown.?

Not to worry. You have this skin growth for 6-7 years and as you mentioned, there has been no change in the size, no color change, no pain , no discharge nor drainage and it does not itch at all. You can continue observing and leave it alone. If you see any changes at all or you are getting concerned, go see a dermatologist so they can do a skin biopsy.