I've cut a tremendous amount of sugar by cutting way way back on Pepsi. I could not stand diet soda, so when I started aiming for under 40% calories from carbs I was trying fairly hard to make sure that I was way under 40% for most of the day, so that my evening snack could include a Pepsi.
I tried adding some low sugar gelatin cup desserts to my diet to have a nice cool dessert on occasion, not expecting much since I usually cannot stand the artificial sweeteners such things use...but to my surprise I was OK with these. That led my to give diet Pepsi and diet Dr. Pepper another try. Nope, still did not like them...but I disliked them a lot less than I used to. The diet Dr. Pepper was close enough to acceptable that I was able to start drinking it a bit, and after a couple of weeks I was OK with it, and after a couple more I liked it.
Pepsi dropped from daily to once or twice a week, and then to none. Everywhere I'd normally want a Pepsi I'm now fine with diet Dr. Pepper. That's cut calories from whatever falls under the "sugar" line on the nutritional information label from 15% of my calories to about 8%.
Of course, as soon as I got to where diet Dr. Pepper was acceptable, I saw an article claiming that new research showed that people drinking diet sodas lost less weight than people drinking regular soda, and sometimes even gained. WTF?
That research, thought, was based on surveys of people who had tried to lose weight for a year asking about their eating habits, so I don't think it is applicable to me. I doubt that most of those people seriously tracked their eating, whereas I have a spreadsheet with almost everything I've eaten for the last 8 years entered.
I suspect that what happened with the people who lost less or gained on diet sodas is that they offset the calorie savings from the diet sodas with more calories elsewhere. If you are trying to cut calories, and you have a regular soda for lunch, you might pass on dessert at dinner because you know that you did something bad at lunch. If you had the diet soda at lunch, you might feel virtuous, and reward yourself by allowing a sugary dessert at dinner which might be more calories than a regular soda.
One suggestion I have for the next time you try to cut sugar is that if you set a daily sugar goal of below X% of calories from sugar then adopt a strict rule of no borrowing against future meals.
What I mean by borrowing is this. Let's say you set a goal of no more than 10% of calories from sugar per day. One way to achieve this would be to have no more than 10% of calories from each meal or snack be from sugar. Another way is to have some meals and snacks be over and some be under, as long as at the end of the day you are overall under.
Borrowing is letting the earlier meals and snacks be over, and then counting on later meals and snacks being under to meet the daily goal.
The problem with borrowing is that you can easy get yourself in a position where it is hard or impossible to get yourself back down to 10% for the day. Now you feel bad and are discouraged.
Instead, try to make the early meals and snacks under, so that the latter meals and snacks can go over and still meet the daily goal. If you do good enough on avoiding sugar during the day, you might be able to have a nice treat in the evening. But note that this presupposes you are keeping track of your sugar, so that when you give yourself a treat at the end of the day as a reward, you won't go over. Without numbers, it is too easy to end up like those diet soda research subjects.