On your device, go to www.office.com in normal browsing mode (i.e. NOT using private browsing or an incognito tab) and sign out using the icon in the top right-hand corner. You should then use the correct email address to log in.
Android: You must log out of Office using your devices "Home" browser. When asked "Are you trying to sign in to Attendr - Student App?" select the three vertical dots in the top right of the screen. The menu will give you the option to open in your home browser e.g. "Open in Chrome". Use this browser to log out of www.office.com
If you are using an Apple device, you must first ensure you are in normal browsing, not private browsing mode.
To do this: