I thought you could make it into an omod, install it (overwrite all the qtp3 files with itself), uninstall it, and it should be gone. I imagine that would also uninstall any other mods that added new textures for vanilla assets, though.
This is perhaps the best way, if you're not using BAIN - which, evidently, you're not.
For flawless protection against this kind of thing forevermore, i suggest the use of BAIN, with OBMM where absolutely necessary.
edit: That is to say, prevention > cure.