To remove an element from a map use the .delete() method.

map.delete(key);

Example:

const map = new Map([[1, 2], [3, 4]]);
console.log(map.get(3)); // 4
map.delete(3);
console.log(map.get(3)); // undefined

This method returns true if the element existed and has been removed, otherwise false:

const map = new Map([[1, 2], [3, 4]]);
console.log(map.delete(1)); // true
console.log(map.delete(7)); // false