The Microsoft NMAKE build process generate builds for
both debug and release version. The entire acdk folder
then contains several Gigabytes of temporaries.
The "NMAKE -f acdk_all.nmake clean" command only
removes half of the build targets. (either the debug or
the release targets I didn't look)
Given the sheer volume of temporaries (several
Gigabytes). It may be referable to delete temporaries
for each subdirectory as the build progresses.