Allow a site owner to kick a user out of a file opened in Excel Online
If you have multiple people co-authoring in Excel Online, there are times when you need to open the file in Excel - typically for advanced formatting, etc. If someone has accidentally left the file open in their browser, there is no way to force them out and keeps the file locked. Although not always intentional, it can create a major headache by not being able to simply kick/close out that particular user from editing.
This is also an issue when trying to restore a previous version of the file, some other user has left the file open and went home for the day.