How do I force an overwrite or reformatting of a locked external backup disc on Mac?

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Level 1

4 points

How do I force an overwrite or reformatting of a locked external backup disc on Mac?

I have recently swapped a Mac book pro for a Mac Book Air and I want to use my old external backup disc with the new machine. I can't delete the old backup info and clear the disc because somewhere amongst the hundreds of files some are locked. Is there any way of forcing an overwrite or reformatting?

[Re-Titled by Moderator]

Original Title: Disc overwriting

MacBook Air 13″, macOS 26.1

Posted on Dec 10, 2025 6:41 AM

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Answer 1

HWTech

Level 9

68,564 points

Dec 10, 2025 9:11 AM in response to MarinePaleo

You will want to select the physical drive to erase instead of the volume. See the following Apple article for details since the physical drives are hidden from view by default in Disk Utility:

Erase and reformat a storage device in Disk Utility on Mac - Apple Support

Edit: Here is an older version of that article from the Internet Archive which includes a picture which I think is extremely helpful:

https://web.archive.org/web/20250909095655/https://support.apple.com/guide/disk-utility/erase-and-reformat-a-storage-device-dskutl14079/mac

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