How to cancel SetScheduledEndTime?

tl;dr

How to cancel SetScheduledEndTime?

Long story

I have a system in my game that I have to use SetScheduledEndTime to make sure that I have a smooth transition between two sounds. But this transition only happens if the player performs a certain action in a short time. So i need a way to cancel SetScheduledEndTime in case user fails to perform the action, so the current audio will continue playing.

Begin able to use SetScheduledEndTime is very important because it is the only way that I can achieve perfect timing. Using update, etc to keep track of time is not option since the results are unreliable.

Have you tried calling SetScheduledEndTime with a new time that reaches to the end of the audio?