How do I make 1 empty partition out of an external USB disk?
This will erase all data that currently exists on the USB drive:


Remove your USB drive.
Open Disk Utility.
In the menu bar, click [View] > [Show All Devices].
Insert your USB drive. You should see the drive appear in the sidebar in Disk Utility as an item whose name is the manufacturer name and model name/number of the drive. Click this item to select it.
Click [Erase] in the top bar.
Enter a name of your choosing.
For the format, choose "MS-DOS (FAT)".
For the scheme, choose "GUID Partition Table". This is required since your drive exceeds 2TiB in size.
Click [Security Options...], move the slider to "Fastest", then click "OK".
Click [Erase].




macOS will enforce the creation of a 200MiB EFI System Partition on GPT-formatted drives. If you want to claim this space, you can either:


format the drive using another tool of another OS (e.g. Windows Disk Management, GParted for Linux); or
use the gpt command (or an equivalent like gdisk) to manually create a single partition which spans the whole drive, which you will then need to format with a filesystem, e.g. create a FAT32 filesystem using newfs_msdos. If you want to create an EXT filesystem, the mkfs.ext? commands (e.g. mkfs.ext4) can be obtained via Homebrew by running brew install e2fsprogs.