I see that I have 2 DELTREEs here, one is presumably from FreeDOS and is by Charles Dye, and the other is dated 1998 and I assume is from Windows 98. Which are you using?

Open up Windows Explorer or xterm or whatever and delete whatever you want.
DOSBox when mounting a host filesystem doesn't need to be able to delete directories to play games but you can request it be added.

Problem is, I'm trying to prune a ~2,8k folder directory, where each folder is named different in DOSBox, as in Windows.
I have copied the FreeDOS files, for later use, thanks!

*edit: FreeDos' deltree function works fine in Dosbox.