I found an artist entry that has a Pixiv sub account for posting AI-Generated images, but that account has stopped posting. Can I remove these links as I don't see any obvious connections with the main account?
If there's no connection between the accounts at all or the artist makes a clear and visible effort to not associate with it, you can separate it into a new artist tag and attach the account there. If there is a link then no the account should stay in the original artist profile along with the rest of the posts.