Well I feel it's really up to the user. Let's take Ajimu Najimi, a user of Complete arsenal. She is 3,402,193,822,311 years old (246 times older than our universe) and possesses 12,858,051,967,633,865 abilites (12,000,000,000,000,000 is 12 quadrillion). There are many instances in the Medaka Box manga in which she sort of, "Lets things happen". She has been sealed away multiple times in the story just because she wanted it to happen and allowed it to happen. It also has to do with creativity. Ex, I could just make it so that all powers except my powers are now gone, or I can reshape this existence into one where only I have powers, or I can just let them be since it isnt as if they can do anything to me anyway. Be creative, if you have limitless power and you come accross a barrier, go around it and not through it
Ajimu is really mostly hype at best.
There are many characters in obscure fictions on the fringes of the internet that transcend 10 dimensional being and transcend infinite cosmic floor dimensions, and possess infinite number if powers, and possess powers that don't even exist yet, that are totally oblivious and inapplicable to the concept of them or any part of them including their powers of "being erased" since they constantly erase themselves and restore themselves like nothing. The worst part is, they are the lowest tiers in their fictionverse and are already countlessly above Ajimu. Ajimu is in really FAR from being "complete" arsenal. It is nothing more than a title applied to someone that theoretically isn't what you call it.
Who says barriers are the only obstacles to solve? Some fictional characters even embody whatever it is you want to do to them and it is totally inapplicable and don't need freaking barriers to defend themselves. You need a true omnipotent to "kill" them.