Who Has Permissions on my Project?
You can navigate to any project's Team: Profile-Based Permissions section to see a list of users/groups/units that have been explicitly given permissions on that project. Any user who has been added to the project team is listed on that page.
There are other ways that users can gain project permissions: for example, a user can be a member of a unit or group that has global project permissions. To fully investigate the catalog of granted permissions, you can use the Permissions Explorer.