取消设置按钮不管用

<input type="button" value="改变颜色" onclick="color()">
   <input type="button" value="改变宽高" onclick="wh()">
   <input type="button" value="隐藏内容" onclick="hide()">
   <input type="button" value="显示内容" onclick="show()">
   <input type="button" value="取消设置" onclick="exit()">
</form>
<script type="text/javascript">
   function color() {
       var mycolor = document.getElementById("con")
       mycolor.style.color = "blue"
       mycolor.style.backgroundColor = "black"
   }
   function wh() {
       var myweight = document.getElementById("txt")
       myweight.style.width = "100px"
       myweight.style.height = "600px"
   }
   function hide() {
       var hide = document.getElementById("txt")
       hide.style.display = "none"
   }
   function show() {
       var show = document.getElementById("txt")
       show.style.display = "block"
   }
   function exit() {
       var quxiao = confirm("你要取消设置吗")
       if(quxiao == true)
   {
       mycolor.removeAttribute("style")
       myweight.removeAttribute("style")
       hide.removeAttribute("style")
       show.removeAttribute("style")