The extent of this ability can vary from user to user.
Some can only break down physical things like matter while others can interact with metaphysical objects like the soul. It differs from traditional
Matter Manipulation or other abilities like them by
only allowing the user to break things down, not manipulate them. Deconstruction users cannot manipulate things they've already broken down to the fullest extent of their ability.
The note says it can't be a
side-effect of other abilities. So long as breaking things down is the abilities'
main effect then the method used doesn't matter as evidenced by how
Scar and
Gildarts can use deconstruction via Alchemy and Magic respectively. With that said, Judging by what we know of Umas I don't think it's a stretch to say that the one that governs the concept of breaking would be capable of directly breaking things down and thus would qualify for Deconstruction.