Models remaining in memory

[Kurt Landen]

I am currently using a method I made which just uses Apache FileUtils to
delete the folder containing my TDB, but if I add named models to the
Dataset, the models will still be accessible in memory even after the
physical models are gone. If I called addNamedModel it will tell me the
model already exists when I delete the TDB folder and re-create it. How can
I fix this?