You're going to have to be more specific. What is it that you are trying to do, and why. Maybe you don't need to do it after all, maybe it's something that we will tell you that you should do.
In general: apps won't brick your systems. they are just apps.
cIOSs are required to run some apps. removing them may break apps, removing the wrong IOS will definaly brick a system, so you normally shouldn't be messing with those unless you are trying to fix a specific problem.
What's the problem that you are trying to solve?