元の生jsを作成し、domを削除します.

id = "canvas1";

//    canvas
var canvas = document.createElement("canvas");
canvas.id = id; 
canvas.width = window.screen.availWidth; 
canvas.height= window.screen.availHeight;
canvas.style.cssText = "position: absolute; left: 0px; top: 0px;pointer-events: none;";

document.body.appendChild(canvas); 

var ctx = canvas.getContext("2d");

//   
var self = document.getElementById(id);
var parent = self.parentElement;
parent.removeChild(self);
//document.body.removeChld(self)      

var list=document.getElementById("myList");
list.removeChild(list.childNodes[0]);