Does an alchemist always have to do his maximum damage with a bomb he creates? For example, a level 5 Alchemist is doing 2d6+5 with his bombs. Could he opt to make the mixture less explosive and do 1d6 or even 1d3 instead? Does he have to do as much damage as he possibly can at all time?
The rules only provide a few, specific options to reduce bomb damage. Those options include reduced damage to keep balanced (why wouldn't you just always use a force bomb otherwise?). That said, most GMs would probably work with you to realize your goal.
As it is something that normaly isn't sought-after, there is no RAW on this. However, I'm sure that most DMs would be okay that you remove a number of dice from your bomb damage.