Debian 12.9
I just downloaded a 30 MiB epub file, but I can discard the images that make most of this space.
Another epub file includes unsolicited advertising with a link to a subscription. I’d like to get rid of it as well.
Is there something I can use?
Sigil https://sigil-ebook.com/
This is in fact a professional editor. If OP is looking into getting balls deep into ebook editing, this is the answer.