One live flow per channel
A channel runs a single live Guided Flow at a time. When you activate a flow, any flow that was already live on that channel is turned off automatically, so exactly one stays live.
Switch the live flow
There is no separate switch control: to change which flow is live, just activate the other one. It goes live and the previous flow drops back to a draft in the same step.
Turning one off leaves none
Turning a flow off does not activate anything else. The channel is left with no live flow until you activate another one, so the AI answers normally in the meantime.
Deleting a flow
A live flow cannot be deleted. Turn it off first, then delete it. Remember that drafts live in the browser where you built them, so a flow you cannot find may simply be in another browser.