If you want to sign out of all your devices as you have lost your phone or computer do the following
Login to Office.com as your HYMS account.
Click on the Account Manager button in the top right hand corner. NOTE It will have your userID on the button e.g. hyabc1. Then choose View Account.
The following menu will be displayed:
Click on Security Info (You maybe asked to re-authenticate at this point)
Click on the Sign out everywhere link