Viewing Users and User Groups
You can view the list of users and user groups registered in the system on the Administration | Users and Groups pages. The content of this page depends on the Configuring Authentication Settings of server configuration and TeamCity edition you have. For example, user accounts search and assigning roles are not available in TeamCity Professional.
Searching Users
On the top of the Users and Groups page there's search panel, which allows you to easily find users in question:
In the Find field you can specify a search string, which can be a user visible name, full name, or email address, or a part of it.
To narrow down the search you can also restrict it to particular user group, role, or role in specific project using corresponding drop-down lists. By selecting the Invert roles filter option, you can invert search results to show the list of users that do not have the specified role assigned.