And if you delete the C partition you won't have an OS to boot to.
If you have a good backup copy and a backup copy of that you can try GPARTED to move the partition.
I have an old Windows Vista system with the C drive capacity of about 76Gb.
I have Unallocated space of 5Gb and then next to it the C drive of 70Gb but the Unallocated space is listed before the C drive.
Have tried to extend volume from the C drive partition but it's grayed out. Have tried to make the unallocated space into usable space and then giving it a hard drive name to see if I can then delete it and then see if I can extend the volume at that point but that didn't assist me.
Any ideas? Would appreciate any help