Originally Posted by KeninMN
With the beer at room temperature, gently pry up on (but don't remove) the cap until CO2 starts to hiss out of the bottle. Once all of the excess CO2 escapes let off on the cap. It should seal back up. If not (or if you're not sure) you can clamp down on it with your bottle capper. Then refrigerate until cold and test to make sure the carbonation level is where you want it. It may take a few times to dial it in to where you want it.
I believe chilling them before doing that is better because it will keep the foam at bay better. If the issue was too much sugar, as long as the bottles are at room temp they will continue to carbonate and be over carbonated. You can or should keep them chilled to keep the yeast dormant. it won't kill the yeast, it will simply slow it. Those bottles should be consumed sooner rather than later.
You can uncap them warm, but I think chilling is better. I would also just uncap and use new sanitized caps.