How to delete a Client ?
You can able to delete the client if they are archived already.
You can only delete clients if you delete all of their projects (which requires deleting all time and expense entries for the client projects).
The clients who are added with active projects are not able to delete.
How to delete a User ?
You can able to delete the user if they are archived already.
You can only delete users if you delete all of their time and expense entries for all the projects.
Users who have Project hours are not able to delete.