fix: removal of cover image

[sshanzel]

Discussed in #1515

^{Originally posted by codegeek October 17, 2024}
I uploaded an image by mistake as cover image, and now I can't delete it. I had to put another cover image at random just to "remove" the one I uploaded. There should be a way to remove cover (and why not, profile) photos.

There should be a "X" button on the top right corner similar to when removing an uploaded cover image for a post.