How to convert a C disk to NTFS format?

How to convert a C disk to NTFS format?

Under CDM, I enter convert C:/Fs: TFs and the current volume label, but the display is:
Because the current volume label is being used in another process, "Conversion" cannot be run.
If you detach the volume first, "convert" may be run.
All opened handles of the volume will be invalid.
Do you want to forcibly unload the volume? (Y/N)

What should I do?

Select y, and then restart the computer. It will automatically switch (note that power is not interrupted during the conversion process, and human interruption is not allowed ).
In addition, once converted to the NTFS format, it cannot be restored to the FAT32 format unless it is re-formatted.

The comments of the questioner on the answer:

Thank you very much. I will continue to select and restart the switch!