Can A Business Prevent Me From Writing A Bad Review Of Them Online? Please Help.

I'm not sure where I should post this, but I'll give it a shot.

The beauty studio where I had my eyebrows done reached out to me from posting my negative review of them online. They said I signed a waiver stating that if I'm unhappy with the result, I should consult them first to work with the solution and not post or slander them online. They think my review is damaging their brand’s reputation which isn’t my intention. I was wrong for keeping quiet throughout the process bc I was the type of person who would rather stay silent due to shyness and not wanting to disappoint others. However, I’ve gotten tired of looking at myself with my uneven eyebrows. It turned out poorly; they were too thick and uneven. This has made me feel self-conscious about my face and my confidence, and I have to fix my eyebrows constantly with makeup.

What should I do? Should I delete the review I already posted because they might sue me for it, or do I have the right to keep it up?