What’s a fitness plan that I can follow to lose excess fat mostly in the lower body parts?

I know spot reduction is impossible and losing fat occurs to the whole body so I need suggestions of a fitness plan that I can follow to lose excess fat especially in the lower body part (bum, upper thigns) I’m slim in the upper body parts but it’s just my large bum that I’m unconfident about. I’m a high school student and I’m not very active, I’m the paperwork type of person.

treadmill 5x a week 30 mins a day guaranteed to lose weight if you eat right also that means avoiding junk food and soda.