This should work without issue. Should is a big word here, you still want a change control if you require them as Murphy will take the moment you pull the first PSU to strike and have the second PSU fail. This is highly unlikely, but there would be the potential as there is a small surge in draw when going from dual PSUs to a single.
run "environment status chassis" to make sure both PSUs are in "OK" status before the move
move the first PSU, run "environment status chassis" after, again ensure both PSUs are "OK"
I would play it very safe here, move PSU 1, wait 5 mins, then move PSU2(no reason other than to make sure the levels all had a chance to level and adjust.)
move the second PSU, run "environment status chassis" and again verify "OK" status
-Scott