WeakMap.prototype.delete()

const weakmap = new WeakMap();
const object = {};
weakmap.set(object, 42);
console.log(weakmap.delete(object));
// Expected output: true
console.log(weakmap.has(object));
// Expected output: false

weakMapInstance.delete(key)

const wm = new WeakMap();
wm.set(window, "foo");
wm.delete(window); // Returns true. Successfully removed.
wm.has(window); // Returns false. The window object is no longer in the WeakMap.