This question already has an answer here:
My goal is a dual boot Linux/Windows 7 PC. It already has windows 7 on drive C, on a 3Tb drive.
I first defragmented this drive, then shrink the drive c partition to the maximum allowed.
The drive is now 1037.17 Gb, but only 42.9 Gb is used space. I only want to use 120 Gb for windows.
When I try to shrink it, after also defragmenting, the system says:
Size available shrink space in MB: 0
I've made a system backup to an external drive and a DVD repair disk.
Can I just trash this partition and restore it to a newly created 120Gb partition?