Hi there,
If you want to extend C drive volume but you find that extend volume is greyed out in Windows 11, that's because there is no free or unallocated space after the drive C partition. Thus, you need to delete a blank or useless partition. It will leave free space or unallocated space next to the primary volume.
If you do not wish to use the "Delete Volume" option under the Disk Management utility, then you can shrink the volume of the partition in order to get free or allocated space.
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