How To Erase Macintosh Hd. Select Macintosh HD then first aid if fail restart your Mac and do that again Go back to main recovery menu Red Cross exit Open terminal clicking on top utilities type resetpassword even if fail left corner click bold text after apple logo and click erase Mac probably it will fail thats why need to do it again then restart Mac open. Set the Format type to Mac OS Extended Journaled Click on the Apply button then click on the Done button when it activates.

The system will not allow that. If asked enter your Apple ID. A panel will drop down.
Use Disk Utility to erase your Mac.
If asked select a user you know the password for then enter their administrator password. Select the partition scheme and format for the disk and click on the Erase button to format the drive. Ad Remove junk viruses adwareget advanced multilayered protection get back GBs of space. Click the Erase button in the toolbar then enter the requested details.

