What I can suggest regarding your requirement to hide the summaries button is to set the showSummariesButton option to false. This option controls whether or not the header summary icon to be shown. It could be set as following:

//Initialize
 $(".selector").igGrid({
     features: [
         {
             name: "Summaries",
             showSummariesButton: false
         }
     ]
 });
 //Get
 var showSummariesButton = $(".selector").igGridSummaries("option", "showSummariesButton");
 //Set
 $(".selector").igGridSummaries("option", "showSummariesButton", false);

Please let me know if you need any further assistance with this matter.

What I can suggest for achieving your requirement is handling the summariesCalculated event. This event is going to be fired when the grid loads initially as well as every time a checkbox value is changed. In this event you could retrieve the count of the checked and unchecked rows and set this as a span`s text. Afterwards, you could just hide the summary rows in order to save your space. For example:

 summariesCalculated: function (evt, ui) {
 var trueValues = ui.owner.summaryCollection().MakeFlag[0].result;
 var falseValues = ui.owner.summaryCollection().MakeFlag[1].result;
 var total = trueValues + falseValues;
 $("#resultSpan").text("There are " + trueValues + " checked rows from " + total);
 $("tr[data-role='summaryrow']").each(function (index) {
 $(this).hide();
});

}

I modified my sample and I am attaching it for your reference.

I hope this will help you achieve your requirement.