First be logged as JIRA administrator and then access the visible only to such user cog icon to select "User Management":
*Before pressing "Export to Excel", you can limit the number of users by "filter user" (before clicking on "Export to Excel" button):
In order to export users to Excel perform "Export to Excel" action:
After clicking it, you may be presented with the below warning:
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Below it, the same prompt enables to select or deselect between possible columns that are to be present in Excel spreadsheet after pressing "Save File":
Other operations are the same as in Export projects to Excel [1.5.x]
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