Unable to remove external disc from Time Machine backup on iMac

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Level 1

16 points

Unable to remove external disc from Time Machine backup on iMac

Hi, I am going to use an external hard drive to store my 'photos' Library app on, it's taking up all my space on my iMac's hard drive.I am running BIG SUR 11.7.10.

I want to use my old (although new disc last year), Time machine back ups disc. I have another disc and have all my Mac backed up.

I am unable to select it in the list under the 'options' on the time machine window. I want to deselect that ext disc then erase it using disc utility as per apple instructions for erasing a time machine ext disc.

How do I fix not being able to select this disc? thanks for help!

[Edited by Moderator]

Original Title: I want to remove an external disc from time machine back up, but I am unable to select it to remove it, thanks for help.

iMac 27″, macOS 11.7

Posted on Jun 24, 2025 04:29 AM

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Answer 1

Top-ranking reply

D.I. Johnson

Level 7

30,971 points

Jun 24, 2025 10:09 AM in response to denise CLARK

The pic you posted is not of the proper location to remove a disk from TM use. You're in one screen too deep. Click Cancel there and you should be looking at a screen that resembles this:

From here you can select the disk you want to remove from Time Machine use.

System Settings... > Time Machine.

FYI, the window you posted is for excluding a drive from being backed up by TM - different than removing a drive from being used as a backup destination drive.

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Answer 2

denise CLARK Author

Level 1

16 points

Jun 24, 2025 04:07 PM in response to D.I. Johnson

HI D. I . Johnson, thanks for your help, I'll show you in the screenshots what I get and what I'm doing. maybe you'll be able to see what I see and what I'm doing wrong. I go back one step and see this, all I can select here is 'select back up disc or 'options' (which was my initial screen shot on my initial post). so I selected 'select back up disc and I get the next screenshot ,

then all I can select is use this disc, which is the opposite of what I want to do. what do you think? where am I going wrong?

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Answer 3

Jun 24, 2025 04:49 PM in response to denise CLARK

You should be clicking Select Backup Disk... not Options.

Then select the disk you want to remove from Time Machine use.

Please see John Galt's contributions in your other thread here.

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