We can also delete properties from objects like this:
The delete operator removes a property from an object.
delete expression where expression should evaluate to a property reference, e.g.:
delete object.property delete object['property']
object The name of an object, or an expression evaluating to an object.
property The property to delete.
Throws in strict mode if the property is an own non-configurable property (returns false in non-strict). Returns true in all other cases.