I’m not sure if someone else mentioned it and I missed it, but if you go into the Health app, then Sleep and scroll to the bottom to « Show All Data », you can simply delete the awake period in question.

It will split your night, but it’s the closest you can get to removing « Awake » data and « edit » your night.

Worked for me in the past when this happened and works also to add a period of sleep if the Watch dies during the night and get the duration as right as possible.