Done :)
-bash-3.2# diskutil erasedisk jhfs+ Save_Macintosh_HD gpt disk21
Started erase on disk21
Unmounting disk
Creating the partition map
Waiting for partitions to activate
Formatting disk21s2 as Mac OS Extended (Journaled) with name Save_Macintosh_HD
Initialized /dev/rdisk21s2 as a 465 GB...