How can I remove a sequence from an AI tree once it has been executed once?

Hello all!
So I am creating a dialogue system using the Dialogue tree, (ala a series of videotutorials here: Unreal Engine 4 Tutorial - Advanced Dialogue Pt.7 - Wrapping-Up - YouTube)
The problem is that if a dialogue exchange does NOT end with removing the hud, how can I set the AI tree to begin, not at the root, but at a specific sequence point earlier in the tree?