While whitelisting wallets to withdraw to is not a mandatory procedure, we strongly encourage it as an additional security measure.
To disable the withdrawal whitelist select the Withdrawal Whitelist option from the drop down menu under your account name.
On this page there are a couple of buttons in the upper right corner, one of which says Disable Withdrawal Whitelist.
Clicking on the Disable Withdrawal Whitelist button will bring up a dialog box that asks you to confirm to disable withdrawal whitelisting. If you have 2FA authentication enabled you will also be asked to enter a 2FA code.
You will see a confirmation message after disabling the whitelist.