TypeError: property "x" is non-configurable and can't be deleted

TypeError: Calling delete on 'x' is not allowed in strict mode (Edge)
TypeError: property "x" is non-configurable and can't be deleted. (Firefox)
TypeError: Cannot delete property 'x' of #<Object> (Chrome)

"use strict";
var obj = Object.freeze({ name: "Elsa", score: 157 });
delete obj.score; // TypeError
("use strict");
var obj = {};
Object.defineProperty(obj, "foo", { value: 2, configurable: false });
delete obj.foo; // TypeError
("use strict");
var frozenArray = Object.freeze([0, 1, 2]);
frozenArray.pop(); // TypeError

"use strict";
delete Math.PI; // TypeError