Well, thinking about that a bit, the ability to destroy anything and everything can actually be exploited to all hell. Just need precision and one can destroy in a specific pattern to create.

Got a solid block of granite? Destroy the unneeded parts and you can build a statue.
Got a sheet of cloth? Destroy bits to make lace (totally stealing from Inheritance Cycle).
Need to make a tunnel in a hillside? Well, there you go!
Random meteor about to destroy the earth? Kyuu!
Some food spoiled? Destroy the concept of inedible from it to make it fresh again.

Nearly all of creation can be made through destruction in one form or another. The only things she wouldn't be able to create through destruction would be life and growth (like plant growth or animal growth) or things that are created through time/pressure/heat/etc (like peat and diamond). Well, maybe...destroy Coulomb's force (ala No Game No Life) in a localized spot for a very specific amount of time can simulate pressure & heat? But I think I may be getting that wrong too. It might have only worked in No Game No Life because it was the planet's core that had that force removed and was using the sheer mass and gravitational pull to pull of that trick. Haa, pun unintended.

And yes, I'm taking the extreme of absolute manipulation of destruction concept for some of these examples, of which Flan most likely is incapable of, but I like to imagine...

And hey, she can be truly valuable in the city demolition's department, at the very least!

Piemur1 said:

Got a sheet of cloth? Destroy bits to make lace (totally stealing from Inheritance Cycle).

Ahhh, the Inheritance Cycle, that brings me back. To this day it's one of my favorite series, infact it was the series that actually got me into reading 200p books.