Deleting abandoned ones.
If i still need more i delete the biggest ones except for their save folder.
If we talk about real games, never happend on my setups HDD, only on my incoming HDD and then i just move stuff around, depending where i have free space.
I remember when the HD max space was lower than 5GB kids this day playing with TB, so if you don't want to use software or you don't trust them try this steps
1. on the search bar type run window will pop type temp window will pop "select all file Ctrl+A" then " Delete them Ctrl+D" if some file not deleted just keep them
2. repeat same steps on step one this time type in run %temp%
3. repeat same steps on step one this time type in run prefetch
4.empty your Recycle Bin
how many free space you get after you done this? hope it help.
Honestly with 8 TB's of internal and 1 TB of external storage I've yet to have this problem :'D.
When I do eventually I think I'd just buy some more MM2 storage.