How can I change or remove the first image of a pattern?

Once a pattern is published, the first image is locked. This is simply because from this point on, the pattern can receive likes, comments, etc on that first image (and any others past that).

To change or remove the first image, simply use the "Duplicate" option to duplicate a pattern, which will create a duplicate, unpublished version of that pattern which you can work with the first image.

Once ready, delete or hide the previous pattern 😉