Hi @rajshar and welcome to the Quick Sight community!
While removing namespaces does trigger the removal of users and groups associated with that namespace, it is an asynchronous process; therefore it may take the system additional time to actually remove those users, like the instance you’re encountering.
So to my understanding, when a namespace is deleted; since the process is asynchronous, that the users will get deleted but it may take some time for the user deletion to process.
In terms of best practices, as there’s no API to move a user between namespaces, therefore the only other option would be to delete the user (separately from deleting the namespace) as that may trigger the action a bit quicker.
Alternatively, you could also create a support ticket to get more personalized assistance regarding your account and whether this might be a bug.
Since we have not heard back, I’ll go ahead and close out this topic. However, if you have any additional questions, feel free to create a new post in the community.