Please keep in mind that after changing your address, the removed address will not be available for use again in any Coinfloor Exchange UK account, including yours.
Please log in to your Coinfloor Exchange UK account and select "My Account" on the top navigation bar and select "Withdraw". Choose "Bitcoin" and check, if the option "Change your bitcoin withdrawal address" is available. If this is the case, you will be able to change your withdrawal address using your 2FA.
In case the option "Change your bitcoin withdrawal address" is not displayed, please contact Coinfloor Exchange UK Support. After confirming and verifying the request with you, your current address will be removed and upon your next log in, you will be able to enter your new details in the "Withdrawal" tab.