I have seen videos on self massage to remove belly fat in one week if you massage 15min a day. is that even possible?

No. You need to reduce your food intake and increase your physical activity. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV vaccine. Wish you good health! Safe sex: https://www.hopkinsmedicine.org/health/wellness-and-prevention/safer-sex-guideline