You could take the chance, but there's little point: the 5-ASAs are the safest drugs for UC by miles and seem to have a protective effective against colon cancer. Might as well stay on them, m8.
This makes sense.
Are you getting enough side-effects to justify going off them? It's a tricky thing to figure out.
I think med-free is obviously ideal, but looking it at objectively, I am uncertain whether it will work on a vegan diet, as the risk of b12, zinc, retinol deficiencies exacerbate UC flares. For example, it is virtually impossible to get the converted form of vitamin A, retinol (not beta carotine) on a vegan diet. Vegetarian might work far better, and you may need to add in things like butter, raw milk, kefir, etc, etc to promote substantial healing.
If you want resources, I'd suggest you look up Jordan Rubin and Jini Patel Thompson. They both have protocols that can get you off meds, but it will require a meat-eating / vegetarian approach. Plant based might be possible but you'd have to load up with butyrate rich (resistant starch) foods like beans, potatoes, plantains, peas, etc.