Delete Map element

---

examples/delete-key/delete_key.go

package main

import "fmt"

func main() {
    grades := map[string]int{
        "Mary": 99,
        "Jane": 88,
        "Bob":  93,
    }
    fmt.Printf("%T\n", grades) // map[string]int

    fmt.Println(grades) // map[Bob:93 Jane:88 Mary:99]

    delete(grades, "Jane")

    fmt.Println(grades) // map[Bob:93 Mary:99]
}