perl -MData::Dumper -e "  
                          %h = ('Message2' => [ '0X026007' ], 'Message4' => [ '0X026005', '0X026006' ] );
                          foreach $k(keys %h) { 
                                  delete $h{$k} if defined $h{$k}[1]  
                          } 
                          print Dumper(\%h)
                       "


$VAR1 = {
          'Message2' => [
                          '0X026007'
                        ]
        };