In order to withdraw funds, hover over "Portfolios" in the top navigation bar and select the investment account you're interested in.
When on the reporting page, click "Transfers" in the top-right corner and look for the sentence which says: "If you need to withdraw funds click here."
A click on the corresponding link will launch the withdrawal process. Type the desired amount - at least £50 - and confirm your choice by selecting "Withdraw funds".
The money you want to withdraw will be instantly deducted from your portfolio and sent back to the bank account associated with your Exo profile.
Please note that it can take up to five business days for the money to reach your bank account.