How to "merge" drives in Windows 10?

Question

Hard disks

1. Windows 10 OS
2. One physical disk.
3. Divided into two logical C: D:
4. If you transfer all data from disk D: to disk C:
5. Delete partition D:
6. Expand partition C:
Did you describe everything correctly? Or what that "stones" will meet?

Answer 1

Everything is correct. I recommend making a backup copy - always on a separate disk

Answer 2

And how can I merge partitions without transferring information from C: to D:?

Answer 3

Do not use utilities for this case. They are dangerous. Use "Computer Management" for this case. Built-in, and does not require reboots.
Computer => Management => Disk Management