Right now user management is done project by project. Only users with the Manage Users permission can perform these actions. The first thing to do is go to the user management section for a project.
Once inside of user management the default view is a list of everyone who was access to your project.
To learn more about what to do from here check out the following articles:
If you need help resetting your own password and not a team member's please check out our How to reset your own password article.