Go to IB's navigation page. Log in with your IB username and password.
Go to "Transfer Funds" via the left menu.
Select "Withdraw Funds", select either "GIRO / ACH or Bank Wire" and fill in your bank account information.
DISCLAIMER: The following screenshots are taken from Interactive Brokers website, provided only as a setup guidelines, and may be changed from time to time subject to Interactive Brokers discretion. Algomerchant is not responsible for any loss or damages caused by inaccuracy and misrepresentation of the information.