I have my packages on a different drive.
You need to move the Packages folder and its entire contents (Official - One Store, and Community Folders), and then in the usercfg.opt, specify the new location.
My sim is on “C” drive, but my packages are on “F”.
My usercfg.opt entry, which is entered at the bottom of the usercfg.opt file, is:
InstalledPackagesPath “F:\Packages”