I won’t ever run the Dark Citadel, but I picked up the questlines for it without realizing what they were for. Now I want them gone from my quest log since I’ll literally never be running it and the quests won’t ever advance.
The quests are Crater of Lost Souls and Dark Citadel Community Challenge.
You can finish the Crater of Lost Souls, it only opens the main hub with a new waypoint to reach.
As for the Community Event quest - that can’t be removed. But you can select if a quest is higlighted on your game screen by clicking on it in your journal. If you want it removed - just make sure it’s unselected. You can’t remove it from your journal.
I agree this is incredibly annoying.
Eventually at some point in the far future when it becomes unacceptably annoying and my eternal character is paragon level 300 I would ask few people to complete it just for the sake of removing that quest and essentially get any associated challenges completed.