If a person running for office concedes the election because he sees defeat, can he say ‘never mind’ if the final vote tally goes to him, or does conceding end it all?
Nope. Conceding does not mean you are out of it. If you concede and then win anyway it may be a bit embarassing but you still won.
Concession has no legal meaning. You may recall a certain candidate in the 2000 presidential election who withdrew his concession in the middle of the night.
Concession in and of itself has no legal meaning, but it does mean that no further legal steps will be taken to challenge.
In practice, concession means “I am letting the counting process take its own course and I will not instigate a recount or mount a legal challenge.” That’s not the same thing as saying that the election process has no affect.
I believe the only candidate for major office to publicly concede and later win was James A. Rhodes, who conceded the 1974 Ohio governor’s race to John Gilligan based on erroneous TV projections, but eventually won by 11,000 votes.
The unasked question is, “Then why do loser concede? Why just they don’t let the count speak for itself?” The answer is that it is just a gracious thing to do when loss looks inevitable. You look a lot better conceding then waiting until the bitter end and just being the loser.
Conceding is just a face-saving gesture, which as repeated above, is in no way binding.