override this file
app/code/core/Mage/Sales/Model/Order/Pdf/Abstract.php
to
app/code/local/Mage/Sales/Model/Order/Pdf/Abstract.php
and Find insertTotals function
foreach ($total->getTotalsForDisplay() as $totalData) {
$lineBlock['lines'][] = array(
array(
'text' => $totalData['label'],
'feed' => 475,
'align' => 'right',
'font_size' => $totalData['font_size'],
'font' => 'bold'
),
array(
'text' => $totalData['amount'],
'feed' => 565,
'align' => 'right',
'font_size' => $totalData['font_size'],
'font' => 'bold'
),
);
}
to
foreach ($total->getTotalsForDisplay() as $totalData) {
if($totalData['label'] != "Tax:") {
$lineBlock['lines'][] = array(
array(
'text' => $totalData['label'],
'feed' => 475,
'align' => 'right',
'font_size' => $totalData['font_size'],
'font' => 'bold'
),
array(
'text' => $totalData['amount'],
'feed' => 565,
'align' => 'right',
'font_size' => $totalData['font_size'],
'font' => 'bold'
),
);
}
}