If you'd like to opt in or opt out of receiving marketing you can do so here. You can also get to the page by taking a link from your account profile screen. Click here to see how to get to the profile screen.
After signing in you'll see the below:
Tick, or untick, the box as required and click on 'Save' to save your choice. Click on 'Log out' at the top right and close the browser window to finish.