When Raven creates a bar that tracks something which has no expiration time (e.g. Warlock's Corruption/Wither or DH's Chaos Brand) being applied to a target which doesn't actually die (e.g. Brann's dinosaur egg in Delves) then it just stays forever until a reload of the UI. Setting the bar to not show when not in combat will hide it after combat ends, but next time you enter combat again those bars will come back and continue to waste space and add confusion.

Here is a screenshot on my DH after completing a Delve - the Discordant Skitterling is the enemy I'm currently fighting, while the Epic Egg and Devilsaur bars are from the Delve that I'd already long left.