Remove macOS from current dual boot system
If you make a significant hardware or software change, then Windows may fail to boot. In these cases, you need to rebuild the bcd file. The software to do this is included in the Windows installation files. So you need to boot to a Windows installer to run these commands. The procedure depends on how your Mac is configured. 

Some items to consider are given below.


Does Windows boot using a legacy BIOS or the newer EFI.
Can you boot Windows from a optical drive, flash drive or other method.


It would be best to have a way to boot to a windows installer, before removing macOS. Then again, you may not need the Windows installer at all.