You can do this through either the ‘Manage Followers’ or the ‘Manage Following’ tabs.
Go to the “Manage” tab on the top of the screen.
Then “Manage Followers” or “Manage Following” side tab.
If the user has a red “Unfollow” button next to their name, it means you are currently following them. This means you can unfollow them by simply clicking on this ‘Unfollow’ button.
If it is successful, the button will change to a green “Follow” button. This gives you the option of following them again.