Resignation cancel

Last Working Day. But you need to have a decent behavior and attitude during notice period with HR and managers. Else they will not accept the cancelation.

I don't think till the last working day would work as I have seen a case when one of my friends tried to withdraw resignation on the last date and HR simply denied it mentioning it's too late now and they cannot revert it.

Discuss with your manager , explain the reason for withdrawing your resignation in the email and loop HR.

Make sure the manager should reply on the top of your email to approve your withdrawal resignation