public class notes2 {

 public list<string> SelectedValue{get;set;}
 
 public list<selectoption> Alloptions{get;set;}
 
 public list<selectoption> Selectedoptions{get;set;}
 
  
   public notes2(){
   getnames(); 
    }
 
  public void getnames(){
  Alloptions= new list<selectoption>();
  selectoption s1 = new selectoption('Ban' ,'Banglore');
  selectoption s2 = new selectoption('Hyd' ,'Hyderbad');
  selectoption s3 = new selectoption('Che' ,'Chennai');
  selectoption s4 = new selectoption('Ap' ,'Andhrapradesh');
  Alloptions.add(s1);
  Alloptions.add(s2);
  Alloptions.add(s3);
  Alloptions.add(s4);
  }
  
   public void Removelist(){
   
    system.debug('the selected values are::'+ selectedvalue);
    
    for(integer i=0;i<selectedvalue.Size();i++){
    
    system.debug(selectedvalue[i]);
   
   /*
       if(RightSelectedValues[i].getValue() == RightSelectedValues){
              //Selectedfileds.remove(i);
             }
    
   */
   
    
    }
   
   
     
   }
}

<apex:page controller="notes2" >
  <apex:form id="fm">
  
   <apex:outputPanel id="test1" >
    <apex:selectList value="{!SelectedValue}"  id="slctedval" multiselect="true" size="5">
      <apex:selectOptions value="{!Alloptions}"/>
     </apex:selectList>
     
     
     <br/>
      
     &nbsp; &nbsp;
     <apex:commandButton value="Removielist"  action="{!Removelist}"/>
       &nbsp; &nbsp;
      
       
       <br/><br/>
      
     
       
        
         
       
  </apex:outputPanel>
   
   </apex:form>
</apex:page>