Sample: dhtmlxCalendar Hide/show Calendar dhtmlxCalendar main page
X

You can hide/show calendar using hide() and show() methods

 
if(document.getElementById("bt").value=="HIDE"){
    mCal.hide();
    document.getElementById("bt").value="SHOW"
}
else{
    mCal.show();
    document.getElementById("bt").value="HIDE"
}