Hi, I have a checkbox area with a button. When I click the button I want the checkboxes that where selected to be desactivated in the click method.

I have a foreach to verify every checkbox but I dont know how to disable then. Any help pls?
public void btnValiderChoixFormulaire_Clicked(object sender, ClickedEventArgs e)
{
//Variables
XPathNavigator formNavigator = this.MainDataSource.CreateNavigator();
XPathNavigator TypeQUESTION = formNavigator.SelectSingleNode("//my:txtTypeQuestion", NamespaceManager);
XPathNavigator chkType_Cat = null;
string strTypeQUESTION = "|";
Categorie InstanceCategorie = new Categorie();
List<Categorie> catList = InstanceCategorie.GetListCategorie();
foreach (Categorie cat in catList)
{
chkType_Cat = formNavigator.SelectSingleNode("//my:chkType_" + cat.IDCategorie, NamespaceManager);
if (chkType_Cat.Value == "1")
{
>>>>>>>>>>>> disable the checkbox <<<<<<<<<<<<
}
}
//Affectation du type
TypeQUESTION.SetValue(strTypeQUESTION);
}thanks