How unselect a feature ithat select with OpenLayers-3.8.2's selectInteraction?

On ol3 3.11.2, the event.selected.clear(); does not exist, so you need to use the selectionInteraction.getFeatures().clear();

You can use clear function. Change deleteFeature function as follow:

deleteFeature = function(event){
    var feature = event.selected[0];
    myLayer.getSource().removeFeature(feature);
    event.selected.clear();
}