How do I remove an EFI boot partition?

Whenever you use Disk Utility to "erase" a drive it always partitions and formats it. If you securely erased the drive, then it really doesn't matter if macOS puts partitions or file systems on the drive.

To wipe the partition table from the drive on a Mac, you can use the Terminal command line utility "dd" to zero out the first section of the drive. You need to determine the drive identifier for the drive you want to "erase". The basic form of the command is as follows, however, you must replace "diskN" with the proper drive identifier:

sudo  dd  if=/dev/null  of=/dev/diskN  bs=100m  count=10

The above command will write 1GB of zeroes to the beginning of the drive.

All the volumes on the drive need to be unmounted before "dd" will write to the drive. If the Finder or Disk Utility ejects the drive instead, then you can use command line to locate the mounted volumes and then unmount them without ejecting the drive.

Remember to substitute the correct drive identifier in place of the "N" in "diskN" in the following commands:

To find all the mounted volumes on "diskN":

mount  |  grep  -i  diskN

Unmount each volume listed from the output of the previous command using the form:

diskutil  unmount  /Volumes/<volume-name>

Example showing the commands and their output where the drive I want to zero is "disk2":

hwtech$ mount |  grep  -i  disk2
/dev/disk2s2  on  /Volumes/Storage
/dev/disk2s3  on  /Volumes/Backup Work

hwtech$  diskutil  unmount  /Volumes/Storage
Volume Storage on disk2s2 unmounted

hwtech$  diskutil  unmount  /Volumes/Backup\ Work
Volume Backup Work on disk2s3 unmounted

Once all the volumes on the drive are unmounted, you can use the "dd" command to zero out the beginning of the drive.