Gulis question is aimed at the timing in the "Combat Phase".
In the "Combat Damage Step", after all the damage has been dealt players may cast spells or activate abilities.
Creatures are removed from combat only at the end of the "End of Combat Step" and according to
Each chosen creature still controlled by the active player becomes an attacking creature. It remains an attacking creature until it’s removed from combat or the combat phase ends, whichever comes first.
which would mean that even after the damage is dealt the creature is still considered an attacking creature, thus could be untapped with Reconnaissance.
The question is whether the damage is undone by this action, basically rolling back the whole damage calculation. I couldn't find any indication why it should do so.