How to hide & disable Expand/Collapse button of JqGrid GroupingView

In your code you are setting the group text as below :-

groupText : ['<input name="chkHideTest" type="checkbox" class="groupHeader" isHidden="1" />   {0}  '],

Two things i added here like below :-
1. Name to the checkbox element like name="chkHideTest" and
2. one custom attribute named 'isHidden' then set its value to 1 for which you want to make it hidden otherwise zero, by checking the data coming from database.

In actuall the expand button is rendered as below code :-

<table><tbody><tr><td style="padding-left:0px;" colspan="8"><span style="cursor:pointer;" class="ui-icon  tree-wrap-ltr ui-icon-circlesmall-minus" onclick="jQuery('#grid').jqGrid('groupingToggle','gridghead_0_0');return false;"></span><input name="chkHideTest" type="checkbox" isHidden="1" class="groupHeader" name="grpHeader">   test  </td></tr></tbody></table>

So the just before element for the group input checkbox is the expand button which you want to disable/invisible there.

So we need to add a new setting for the grid as below which will be fired just after the load completion of the jqGrid as mentioned below :-

loadComplete:function(){
        $.each($("input[name='chkHideTest']"), function(i, obj){
	        var isHidden= $(obj).attr('ishidden');            
            if(isHidden)
            {
                $(obj).prev().hide();
            }
        });
    },
}

So this will hide the specific expand button which you dont want to view or else you can disable it by modifying the code a bit.

Hope this will definitely of help to you.