I quick fix would be to just stop the workout and start anew. Or just reduce intensity to slow pedal that extra accidental time, possibly even back pedal. I know it’s not what you want, but it’s an easy workaround.
EDIT: Upon thinking about it, TR doesn’t have an “undo” option anywhere in their platform. Expecially in the calendar where it is truly needed! I’m guessing @Nate_Pearson only believes in nothing short of full committal to your choices 
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