WHO suggests keeping free sugars below 10% of daily calories, and below 5% for added benefit. A can of cola is around 7-9 teaspoons of sugar (approximate).
Alternatives
Water with lemon, unsweetened tea, or soda water with a little fruit. Cut down gradually.
This is general information, not a substitute for medical advice. If you have a medical condition, are pregnant, or take regular medication, talk to your doctor first.