FWIW: simply removing records from your repo db (in particular the blob table) _will_ corrupt it. Fossil stores deltas and other metadata which span blobs, and it's not trivial (and in many cases not possible) to separate them post facto. Hypothetically it would be possible to "pop" the top-most change from a repo, then repeat that, going all the way back to the start of the repo, but it's not possible to remove something from in the middle without the equivalent of a 4-way heart bypass surgery.