Fix email sync issues or remove a device from your Exchange Outlook Web App.
Exchange Outlook Web App (OWA) shows the mobile devices that you use to connect to your mailbox. If you're no longer using a device or a device isn't syncing properly, you can delete it from this list.
1. Sign in to Outlook Web App
2. Choose Settings next to your name in the upper-right corner of the page, then click Options.
3. In the left navigation bar, under General, choose Mobile Devices.
4. Select your phone in the list, and then select Remove to delete the device partnership.
5. Select Yes in the confirmation box.