If you've found mold on one bud, chances are there's going to be more of it throughout the plant. If the trichs are anywhere near ready, I would advocate chopping in order to save the harvest... If the mold you've found is bud rot (you don't say WHICH mold it is), I can pretty much guaratee you the plant has more of it... Read this article on bud rot (botrytis): https://www.cannaconnection.com/blog/18536-how-to-deal-with-prevent-bud-rot-in-cannabis-plants
If it's powdery mildew, you can spray with 1tsp/gallon baking soda but that will only kill the PM that it actually hits so you'd have to be VERY thorough in your spraying..
Good luck!