Clicking the "remove" button in the link context menu on a pre-existing link (internal/external/…) removes the link, as expected. Doing so on a newly-created link (in this edit session) doesn't do anything. Is the wrong bit of the linmod getting read or something odd?
I think this is me finding T143261: Paste identical annotated content into (end of?) an annotation serialises very poorly because it gets double-annotated again and not realising it (re-creating links). Looks to be solved in that work.