Disk Partition Management in Windows

Disk Management — built-in

Press Win+X → Disk Management. Right-click a volume to: Extend Volume, Shrink Volume, Delete Volume, or change drive letter.

Shrink limitation

Windows cannot shrink a volume past unmoveable files (pagefile, hibernation file, MFT zone). Disable hibernation (powercfg /h off) and move the pagefile temporarily to free more shrink space.

MiniTool Partition Wizard Free

For merging non-adjacent partitions or moving partitions — operations Disk Management cannot do — MiniTool Partition Wizard Free is the most reliable free option. Always apply changes when booted from its bootable USB for system partitions.

Extend C: after D: deletion

If D: is directly to the right of C: in Disk Management, delete D:, then right-click C: → Extend Volume → accept defaults. If D: is not adjacent, use MiniTool to move unallocated space.