Quick update on my extraordinarily interesting pc life.
Learnt a few things:
1. DOS is quicker than other usual forms of file deletion. 2. del won't work for folders, need to use command RD (= remove directory). Also deltree is no longer usable if you have XP as your OS. 3. files spelt with with a space must be wrapped in quotation marks or won't be read properly. 4. it was necessary to add /s and /q to the end of the command to achieve deletion.
S = Removes all directories and files in the specified directory in addition to the directory itself. Used to remove a directory tree. /Q = Quiet mode, do not ask if OK to remove a directory tree with /S.
Anyway, I'm still a good hour into it, and it seems to be working and much quicker than windows. Should be finished in another hour.
final command was rd C:\"program files"\AmiBroker\Reports/q/s