deleteKeyValue(obj, key)

Remove the property identified by the String or Symbol key from the Map-like object obj, if possible. Property definitions may interfere with deleting key values; the behavior on obj if obj[key] cannot be deleted is undefined. The default use of the native delete keyword can be overridden by obj if it implements @@can.deleteKeyValue.

var foo = new DefineMap({ bar: "baz" });
var quux = new CanMap({ thud: "jeek" });

canReflect.deleteKeyValue(foo, "bar");
canReflect.deleteKeyValue(quux, "thud");

"bar" in foo; // ->  true  -- DefineMaps use property defs which cannot be un-defined
foo.bar // -> undefined    --  but set values to undefined when deleting

"thud" in quux; // -> false
quux.thud; // -> undefined