No need as this is an unrated game simply resign and you will loose no points in your rating.What is the purpose of taking back 45 moves, when a simpler solution is available?

When you play a takeback, unrated game it is in my opinion for the purpose to learn beyond the wrong move made.

You do have to play against a much stronger opponent and I would suggest 1900+ rating.

As at this level on this site the comprehension of the game by the stronger player, though not at master level, is quite respectable in my opinion.

If you do play a takeback game, you have to play enough moves to convince your student that after 2, 3, 4 moves he has not played the right move, by demonstarting the lines of play not just saying this is not right, we need here indepth analysis and suggestions.

You never ever, even when it seems a blunder take a move back after one single move, that is a no no, proof is in the putting or the position that follows and clear board positionning is essential to convince your opponent 100%, so play as many moves to demonstrate the inadequacy of the move.

Bottom line if you play a takeback unrated game it is to improve yourself.

If you think that I can help you, do call on me.

It is unfortunate that the message box, when playing against an unrated or takeback opponent is not available for public viewing, I for one would elkect in all of my games to make our discussion public.

If the blunder was to hang a major piece (with no compensation) - and there were clearly better alternatives available, what would be the point of proceeding further before acknowledging and correcting the mistake?

so if you takeback an opponent's move, can you do takeback again to undo your previous move also? or do you have to switch off doing takebacks?

Within a TAKEBACK game, an extra button "TAKEBACK" is displayed throughout the entire game, alongside SUBMIT MOVE, OFFER DRAW, CONDITIONAL MOVES. Both sides can takeback at any time. When it is your move, clicking on TAKEBACK undoes your opponent's previous move - and it becomes their turn again.

When it is NOT your move, clicking on TAKEBACK undoes your previous move - and it becomes your turn again. This can be repeated all the way back to the beginning of the game. You can't undo CHECKMATE (or once the game is over). 

There is no way out of TAKEBACK mode within a TAKEBACK game.