Hello, you can do this formatting on Windows installed as a Boot Camp partition so you can use the easy method.
For macOS, you'd have to copy everything off to another drive, then format it as FAT32. Because Mac can't write to the NTFS drive, so you should do a backup before this step.
The best way to use your NTFS both on Mac and Windows without formatting is using NTFS driver for Mac. iBoysoft NTFS for Mac is a professional tool that enables Mac fully read and write on Mac
For formatting, you can try:
(1) Format the drive in Mac Disk Utility.
(2) Change the drive file system in Mac Terminal.
Be careful to backup all the data, then after formatting, you move them again.
Also read: How to Convert External Hard Drive from NTFS to FAT32 on Mac
