Libraries that have Tipasa or WMS can pull patron reports that list all users. See How can we pull a patron report in Tipasa? and Circulation Patron Full report.
For libraries that do not have Tipasa or WMS, there is currently no way for the system to display all user accounts in WorldShare, but you can search for users by email domain. So if all of your users have the same email domain, then you can effectively view a list of all users. You must have an Admin role to complete the following steps: