If you go and do a disc clean up then select more options. Go down to the System Rstore section and then clean up you can delete all but the last restore point. Only do this if you are happy that your system is running well. You will be surprised by how much space on your hard drive will be freed up. I do this every so often.
By default, System Restore is allocated 12% of your hard disk space; it will not necessarily occupy it. 14 GB is a little excessive - Microsoft set the minimum of 200 MB, so there is plenty of room for manoeuvre between those limits.
Whilst 12 GB is allocated, it may not be occupying it and other processes may be occupying space. There is a handy little utility called Tree Size: click here which will show you how much space is being occupied and by what.
If you want to recover some space, try the following:
1. empty your temp folder
2. empty the recycle bin
3. reduce the size of the recycle bin
4. reduce the space allocated to temporary internet files