Face it, drinking soda just adds empty calories to your diet.
You could change to sugar free or zero soda but that's probably even worse than drinking regular, sugar laden, soda. The nasty additives make diet soda a bad choice (look up aspartame if you need convincing). Plus your body doesn't differentiate too well between real sugar and pretend sugar, so you get a lot of the bodily reactions with diet soda that you do with regular soda.
So, how do you stop drinking soda? Not just now or today or this week. But altogether. Except maybe for special occasions.
First off, make sure there's none in the fridge. Not having soda in the house makes it a conscious effort when you next want to slurp down some soda.
Secondly, if you've been used to drinking cola, don't go cold turkey. The caffeine takes time to leave your system, so ease out of drinking cola gently.
Third, keep some sparkling water in the fridge and drink that when you get the urge for soda. Maybe add a slice of lemon or lime to spruce up the tast.
Fourth, drink plenty of water. You should be doing this anyway - the recommendation is 8 glasses a day.
After a while - likely about two weeks - you'll find that your tastes have started to change. What appeared attractive to you in the shape of fizzy soda is no longer as attractive. You'll find yourself instinctively asking for something other than soda. Maybe water. Maybe tea or coffee (but don't overdose on that as a soda substitute!).