Any character should be able to left click on any non-player character to talk to them, and have a dialogue option to ask them to leave. Recruited characters can not start a conversation with the player character.
That's odd! clicking on the character did option a talk bubble. I thought I tried that initially, but it must've been a mouse slip that didn't bring up the bubble. Thanks for your remedial lesson.
Btw, the dismissed character walked away. Do you think I would find her where we initially met? I only dismissed her as a test.