You are unable to amend your bank account details by submitting a new application or cancel the online application while it is pending activation. You can update your bank account details after it has been activated, which will generally take 12 hours for PayNow NRIC-linked bank accounts, and up to two working days for other bank accounts. 

If the changes made to your bank account details are unauthorised, please contact your bank to freeze your bank account immediately and reset your Singpass. If you are age 55 and above, you can also activate the CPF Withdrawal Lock under Account settings to instantly disable online withdrawal.