[SalesForce] Dynamically add and remove rows in lightning

I have to dynamically add and delete records in my lightning page.

I have done with adding the rows but I am not getting how i will remove the records. Rather I am not understanding how I will get the record that i have to delete as an parameter.

App

<aura:application >
<c:AddDeleteMapping>
</aura:application>

Component

<aura:component controller="AddMappingController">  
<aura:attribute name="wrappers" type="OpportunityRollOverStageMapping[]"  />
<aura:handler name="init" value="{!this}" action="{!c.doInit}" />
<aura:registerEvent name="deleteExpenseItem" type="c:deleteExpenseItem"/>

<table>
    <tr>
        <th class="head">Count</th>
        <th class="head">From Stage</th>
        <th class="head">To Stage</th>
        <th class="head"></th>
    </tr>
    <aura:iteration items="{!v.wrappers}" var="wrap">
        <tr>
            <td class="cell">
                <ui:outputText value="{!wrap.count}" />
            </td>
            <td class="cell">
                <ui:outputText value="{!wrap.fromStage}" />
            </td>
            <td class="cell">
                <ui:outputText value="{!wrap.toStage}" />
            </td>
            <td class="cell">
                <ui:button label="Delete" press="{!c.deleteMapping}"/>
            </td>
        </tr>
    </aura:iteration>
</table>
<button onclick="{!c.addMapping}">Add Mapping</button>

lightning Controller

({

doInit : function(component, event, helper) {   
    helper.GetStageMapping(component);

},
addMapping : function(component, event, helper){
    helper.AddStageMapping(component); 
},

deleteMapping : function(component, event, helper){
}})

Helper

({

GetStageMapping : function(component){
    var action = component.get("c.getFromStageAndToStages");
    var responses ='';
    action.setCallback(this,function(response){
        responses = response.getReturnValue();
        var wrappers=new Array();
        if(component.isValid()){
            var wrappers=new Array(); 
            for (var idx=0; idx<responses.length; idx++) {
                var wrapper = { 'count' : responses[idx].count,
                               'fromStage' : responses[idx].fromStage,
                               'toStage' : responses[idx].toStage
                              }; 
                wrappers.push(wrapper);

            }
            component.set("v.wrappers",wrappers );
        }

    });
    $A.enqueueAction(action);
},    

AddStageMapping:function(component){
    var action = component.get("c.getAddedStageAndToStages");
    var responses ='';
    var wrappers=component.get('v.wrappers');
    alert('wRAPPERS: '+ wrappers);
    var mappRecords = new Array(); 
    for (var idx=0; idx<wrappers.length; idx++) {
        mappRecords.push(wrappers[idx]);
    }
    var ListJSON=JSON.stringify(mappRecords);
    alert(ListJSON);
    action.setParams({
        OpportunityRollOverStageMapping : ListJSON
    });

    action.setCallback(this,function(response){
        responses = response.getReturnValue();
        var wrappers=new Array();
        if(component.isValid()){
            var wrappers=new Array(); 
            for (var idx=0; idx<responses.length; idx++) {
                var wrapper = { 'count' : responses[idx].count,
                               'fromStage' : responses[idx].fromStage,
                               'toStage' : responses[idx].toStage
                              }; 
                wrappers.push(wrapper);

            }
            component.set("v.wrappers",wrappers );
        }

    });
    $A.enqueueAction(action);
},    

DeleteMapping : function(component, expense, callback) {

}

})

Apex Controller

public class AddMappingController {

public static List<OpportunityRollOverStageMapping> listStageMappings;
public AddMappingController (){
    listStageMappings = new List<OpportunityRollOverStageMapping>();
}

@AuraEnabled
public static List<OpportunityRollOverStageMapping> getFromStageAndToStages(){
    listStageMappings = new List<OpportunityRollOverStageMapping>();
    List<OpportunityRollOverStageMapping> wcList = new List<OpportunityRollOverStageMapping>();
    for(integer i =0 ; i< 2; i++){
        OpportunityRollOverStageMapping opportunityRollOverStageMap= new OpportunityRollOverStageMapping();
        opportunityRollOverStageMap.count = i;
        opportunityRollOverStageMap.fromStage= 'str'+i;
        opportunityRollOverStageMap.toStage= 'str'+i;
        listStageMappings.add(opportunityRollOverStageMap);
        wcList.add(opportunityRollOverStageMap);
    }
    return wcList;
}


@AuraEnabled
public static List<OpportunityRollOverStageMapping> getAddedStageAndToStages(string OpportunityRollOverStageMapping){
    Type stageMappingType = Type.forName('List<OpportunityRollOverStageMapping>');
    List<OpportunityRollOverStageMapping> parameterList = (List<OpportunityRollOverStageMapping>) JSON.deserialize(OpportunityRollOverStageMapping, stageMappingType);

    List<OpportunityRollOverStageMapping> wcList =new List<OpportunityRollOverStageMapping>();
    wcList.addAll(parameterList);

    OpportunityRollOverStageMapping opportunityRollOverStageMap= new OpportunityRollOverStageMapping();
    opportunityRollOverStageMap.count = wcList.size();
    opportunityRollOverStageMap.fromStage= 'str'+wcList.size();
    opportunityRollOverStageMap.toStage= 'str'+wcList.size();
    wcList.add(opportunityRollOverStageMap);
    return wcList;
}

@AuraEnabled
public static string  deleteExpenseItem(string OpportunityRollOverStageMapping) {
    return 'srk';
}}

Add the element as new row is done. But how will i delete the specific selected row from the list?