Programs installed on the old drive will not (as you've found) show up in the Add/Remove Programs control panel. There are several things you can do to free up space:
1. If you've already gotten all the files you want to save off of the drive, then you can just quick-reformat
it thereby freeing up (almost) the entire drive.
2. If you don't want to reformat then you can delete the programs by browsing to the Program Files
(and/or Program Files (x86)
) folder on the old drive and delete either some or all of the contents (or just delete the folder itself.) Most applications get installed to this location so deleting it will delete the programs. You may also want to delete the Windows
folder as well since it will be taking up a large amount of space too.
3. Repartition the drive to create multiple new, blank volumes (see here
, and here