what if macintosh HD - Data is also there? Does it need to be erased?
Trying to erase my hard drive. What if Macintosh HD - Data is also in the menu bar. Does it need to be erased?
Erasing by Volume-names will not accomplish what you need.
Choose "Show all Devices" off the Disk Utility View menu
select the physical device by its immutable hardware-name like Seagate xyz4321 (NOT Macintosh HD, NOT disk3s2)
ERASE