What should a person do who withdrew an amount from his bank account exceeding his entitlement after leaving his job at a government institution?

This money does not fall outside of three categories:

1. Unlawful bank interest: It must be spent on general Muslim welfare for disposal, and not returned to the bank.

2. Money mistakenly disbursed to you by an institution: It must be returned to them.

3. Money that is rightfully yours: It is lawful for you.

You must research, investigate, and contact the institution and the bank to ascertain the truth of the matter.