Board Thread:The Quarters - Q & A/@comment-80.233.37.44-20181022213233/@comment-25085701-20181023191849

First of all, are you the quest initiator and/or party leader? If you're neither of these, then you might not have GUI control over the participants in the quest -- it's been a long while since I've been questing, so I'm not sure if someone can leave a quest from the party screen -- check the Quest list in your party page, and there might be a control next to your name. However, there's definitely a way to leave a quest using the API commands, which is a bit complex.