Stack one on top of the other? There isn't going to be a cheap and quick solution for putting them next to each other. Removing drywall is a bad idea for a variety of reasons, not the least of which being that the doors probably wouldn't have enough room to operate properly.

Exchange one of them for a 27" cabinet if you can. Failing that, it might be feasible to have a handyman cut one of them down, depending on the style of doors they have.

Easier to amend the cabinets, not the walls! What are they made of?

Check whether the whole space is square and if the problem is for the whole height of the cabinet. If it is, perhaps you can remove one whole side of one cabinet, perhaps one of the centre ones? (door-function dependent, obviously)

But personally, I'd change up the plan: maybe hang one cabinet, and put shelves in the remaining space. You can perhaps even hang the cabinet doors on the shelves.

KarinL