How-to Make a Virging Disk on Mac OS X 10.11 El Capitan
The Mac Tutorial Shows You Step-by-step How-to Delete All Partitions and Remove also the Partition Table to leave pure Free Space for a Drive on Mac OS X 10.11 El Capitan.
The GUI Function to make this is Easily by Mac ‘Disk Utility’ have been Dropped on Mac 10.11 El Capitan!
So to Achieve this is Usefull Task (also when You whant just write an Bootable ISO to a Disk) we’ll make use of the Mac Terminal Shell.

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Open a Shell Terminal emulator window
(Press “Enter” to Execute Commands) -
Find the Disk to Erase:
diskutil list
Before the Disk should look like on command output:
/dev/disk3 (external, physical): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *8.0 GB disk3 1: EFI EFI 209.7 MB disk3s1
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LogIn as SuperUser:
sudo su
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Erase All Partitions on Disk
Triple Check the Command before Execution! (You may Destroy another one Disk…)diskutil eraseDisk free macInstall /dev/[MYUSBKEY]
Example:
diskutil eraseDisk free macInstall /dev/disk2
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Drop the Partition Table:
dd if=/dev/zero of=/dev/[MYUSBKEY] bs=1 count=1024
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LogOut as SuperUser:
exit
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To the End the Disk will show to contain only Free Space:
diskutil list
With now in the output something like:
/dev/disk3 (external, physical): #: TYPE NAME SIZE IDENTIFIER 0: *8.0 GB disk3