removing chracter

in our project we are making a game on which we are making words from letters on the ball. when we click a ball the letter written on it appear. when we click the ball again the word disappear. the problem is that i want that when i click on the ball second time the word disappear and the preceding words move backward to fill it place what should we do??

     static var nextPos = 200;
     static var word: String;
     var sel: String;
     var isClicked : boolean=false;
     var xpos: float = 200;
     static var i:int=0;
     
     function start()
     {
      word="";
     }
     function OnMouseDown() 
     {
         if (!isClicked) {
            isClicked = true;
            xpos = nextPos;
            sel=OnGUI();
            word=word+sel;
           
            nextPos += 8;
            i++;
              
           }
     else if(isClicked)
       {
       isClicked = false;
       xpos = nextPos;
       i=nextPos-8;
       xpos=nextPos-8;
       nextPos -= 8;
       }
       }
         
         function OnGUI()
         {  
         
            if (gameObject.name == "Sphere(Clone)" && isClicked )
            {
                   GUI.Label(new Rect(xpos,260,400,100), "A");
                   return "A";
                          
            }
            
            else if (gameObject.name == "Sphere 1(Clone)" && isClicked )
            {
                   GUI.Label(new Rect(xpos,260,400,100), "B");
                   return "B";
                   
            }  
            
            else if (gameObject.name == "Sphere 2(Clone)" && isClicked )
            {
                   GUI.Label(new Rect(xpos,260,400,100), "C");
                   return "C";
                   
            }
            
            else if (gameObject.name == "Sphere 3(Clone)" && isClicked )
            {
                   GUI.Label(new Rect(xpos,260,400,100), "D");
                   return "D";
               }    
           GUI.Label(new Rect(xpos,280,400,100), "V" + i);
           GUI.Label(new Rect(xpos,310,410,110), word);                      
         }