ITC Reversal

In your next GSTR-3B just deduct that amount from ITC and prepare a reconciliation statement for your reference and also for GST Audit purpose.

What about Financial Year, as it's jumping.

You cannot help it as there is no revision option.

It would be better to reverse the excess credit taken rather to reduce it from ITC. It may be bona-fide for you i future, as you yourself declared the reversal & did not want to hide by adjusting ITC. Reducing ITC may not be helpful to proof bona-fide and to avoid penalty.

This is my personal opinion in order to comply with law. For other solution the case to be examined by facts.