Yes, why do companies do this ? "Throw a user into the deep end".
Surely they must have a policy for "neutering" computers before
allowing transport outside the company premises.
The version of Windows on the computer is likely Enterprise,
with a VLK for a license. I'd have suggested "level and reload"
as a shortcut to getting the job done, but right away, the
licensing of that machine is an issue.
So if there is software of great value on there, and the desire
is to continue to use it, you may just be better off leaving
the settings alone. Or, if the IT department has a proper cleaning
procedure for computers like that, see if the IT department
will now finish the job.
If this was a computer at where I worked, it would probably
have been nuked and the original Dell stuff put back on it.
They wouldn't allow preservation of all settings, just
back the truck up and cart away the PC, without some
amount of maintenance first.
If the machine had the recovery partition on it, you could
restore to factory that way. That would use the royalty OEM
license the computer originally came with. When an IT
department receives a new computer like that (with factory
setup), they throw any discs into a junk box in the
preparation area (never to be seen again), then load
the corporate image, VLK license key and so on. The
original factory (OEM) license key is ignored. To put things
back, if the recovery partition was still on the machine,
you could use that, but odds are, the IT processing
procedure likely removes every speck of original
content (delete that 15GB partition). In which case,
locating recovery media from Dell or whatever, would be
the best option (instead of wasting money on a retail
OS purchase for it).