Just disable System Restore and reboot. This should delete all restore points.
Then setup System Restore to allow between 2-5GB . This should cover most short term issues that
System Restore is handy for (botched user changes, recent software installs, or similar system changes).
Too large a System Restore tends to add to problems as it will uninstall recently installed programs\games, updates and user tweaks.
Best to just have a couple of restore points that cover a week or two, and keep doing as you are with a backup of
your main system on an external drive (internal is not without risk).
*drifts off topic....
- I reckon the best way to manage games is to never install to the default location - Program Files (X86)
or anywhere else in C:\ . This allows you to keep C:\ size to a minimum, which helps make for quicker system images\clones.
Since the advent of SSD's I've been using a 120GB SSD for Windows, personal data such as music, etc. Lightweight programs
(excluding things that are closely associated with the OS such as Firefox, security software, keyboard\controller profiling programs etc),
are all on another small Partition on the SSD as well.
All games are on separate drives, but a partition on the same drive as C:\ is good too as you don't have to image\clone that partition.
- Personally... I see to many suggestions to 'take ownership' of this, that and the other thing. Logging on with an Admin account
should give enough permissions to do whatever any User needs in most instances.
Note, that when it comes to the dread Windows Apps folder (which does not have to be installed in C:\ either),
all giving yourself permissions is good for is to be able to see how much drive space the games are using
(you still cannot do anything with the game files), but this anti-PC gamer nonsense can be avoided by not buying
games from the Windows Store. AKA... GFWL mk2.
.