func parentPath(path string) string {
	keys := strings.Split(path, ".")
	parentPath := strings.Join(keys[0:len(keys)-1], ".")
	return parentPath
}
returns the path without the last key
parentPath("a.b.c") whould had returned "a.b"
package mxj
import "strings"
func (mv Map) Remove(path string) error {
	m := map[string]interface{}(mv)
	return remove(m, path)
}
func remove(m interface{}, path string) error {
	val, err := prevValueByPath(m, path)
	if err != nil {
		return err
	}
	lastKey := lastKey(path)
	delete(val, lastKey)
	return nil
}
func lastKey(path string) string {
	keys := strings.Split(path, ".")
	key := keys[len(keys)-1]
	return key
}