JQUERY how to get clicked tr or td table's ID ??

Use the below line of code .

$(this).closest('table').attr('id');

DATATABLE : how to remove pagination if no record found from the database

Add following line of code into your datatable definition 

"fnDrawCallback":function(oSettings){
var totalFoundRecords = oSettings._iRecordsDisplay;
if((totalFoundRecords!=null && totalFoundRecords>0) == false){
$(oSettings.nTableWrapper).find('.dataTables_paginate').hide();
}
},