Can I change my bank account number, if it is incorrect and my refund has already been accepted?

Maybe, if you act fast. Phone the IRS and/or state taxing authority and speak to a representative. Have materials at hand, e.g., your 2018 tax return, to verify your identity.

You cannot change your bank information since your return has already been accepted.  The IRS (& State) will automatically switch you to receiving a check once the bank rejects the deposit because of the wrong bank information. It can take 4 to 6 weeks to receive the check.