What is a word that describes when you try to fix something bad but destroy something good in the process?
Solution 1:
Situations as the one you are describing are generally referred to as:
out of the frying pan into the fire (saying)
when you move from a bad or difficult situation to one that is worse
(Cambridge Dictionary)
Solution 2:
To throw the baby out with the bathwater. LINK
To discard something valuable or important while disposing of something considered worthless, especially an outdated idea or form of behavior.