Settings object key.
If Undefined, settings for all objects are deleted.
For details see Settings automatically saved in the system storage.
Key of settings to be deleted.
If Undefined, settings with all keys are deleted.
Name of the user whose settings are to be deleted.
If Undefined, settings of the all users are deleted.
If user, which is not current, is specified, i.e. when attempting to call the settings which do not belong to the current user, then the DataAdministration right is required for the current user.