Can I convert my resident bank account to NRE account?

No, according to the FEMA, an Indian who becomes NRI cannot convert his bank savings account to an NRE account. The reason is an NRI cannot deposit income earned in India to an NRE account. Resident account can be converted to an NRO bank account only.

However, if you wish to have an NRE account to maintain income earned overseas, it is advised to close your current resident account and open a new NRE account.