Can't convert former Time Machine drive [SOLVED]

[anp27]

I'm using 10.13.2. I have a 500GB drive that I recently used as a Time Machine backup drive but I bought a bigger 2TB one which I'm now using instead. I'd like to wipe the 500GB to use as a 'normal' drive but I every time I try to do it, it says the process has failed. Any help?

 

[BLUEDOG314]

Either disk utility is not properly unmounting the filesystem or there is some partition map damage. Try this first:

Open terminal with the drive plugged in and type "diskutil list" and hit enter. Find the device identifier for the external drive, it will likely be "disk1" as the internal drive is usually "disk0". If your mac has a fusion drive it will probably be "disk2". Identifying this correctly is important. Now do "diskutil unmountdisk diskX" where X is what you determined before. Now do "diskutil erasedisk jhfs+ Backup diskX" or replace Backup with what you want to name the drive, using quotes if there is a space in the name. Report back if this does not work.

 

[NoBoMac]

Need to ask a stupid question: you did remove the drive from the list of drives in Time Machine preferences? Could see that preventing one to do anything with the drive.

 

[anp27]

Open terminal with the drive plugged in and type "diskutil list" and hit enter. Find the device identifier for the external drive, it will likely be "disk1" as the internal drive is usually "disk0". If your mac has a fusion drive it will probably be "disk2". Identifying this correctly is important. Now do "diskutil unmountdisk diskX" where X is what you determined before. Now do "diskutil erasedisk jhfs+ Backup diskX" or replace Backup with what you want to name the drive, using quotes if there is a space in the name.

Oh my goodness, this worked perfectly, thanks so much!

Need to ask a stupid question: you did remove the drive from the list of drives in Time Machine preferences? Could see that preventing one to do anything with the drive.

No, I didn't do anything at all actually..