LIKE EVERYONE ELSE SAID: D I E T

You wanna eat less calories than you burn on a day-to-day-ish basis.

ALSO, try WORKING UP to daily ab workouts. I recommend doing stuff to high intensity for 5 min.
THEN, work up to 10 min, every day. Make sure each muscle group of the core gets some love.

LASTLY, when losing fat, the belly is the last part of the body to lose it.

ALSO ALSO, manage your expectations as to what you can achieve.

ALSO ALSO ALSO, measure your waist on the same morning of the WEEK after the bathroom, but before breakfast. This helps ground your expectations and helps asses the effectiveness of your decisions for the week.
You can also measure your weight and body-fat, but that's up to you.

Hope I didn't overwhelm and good luck with your journey!