You really need to start using placeholders (?) in your SQL like this. ;

sub deletecontact{
  my $message;
  my $sql = 'DELETE FROM test.addressbook where last_name = ?';
  my $sth = $connect->prepare($sql);
  my $rd = $sth->execute( $q->param('lname1') );
  if ($rd == 1){
    $message =  q(Record has been successfully deleted!!!);
  } else {
    $message =  q(<b style="color:red">Error! Couldn't delete record</
+b>);
  }
  return $message;
}
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poj