Remove a user from a tenant.
The tenant owner or any user with has_user_management_permission in the
tenant (e.g. users in the Admin role) can remove users from the tenant. The
tenant owner cannot be removed from their own tenant. This removes the user
from all roles in the tenant and revokes their permissions on datasets
belonging to the tenant. Data owned by the removed user (e.g. datasets they
created) remains in the tenant.
Returns a success message indicating the user was removed from the tenant.
has_user_management_permission (e.g. Admin role) in the tenant