use strict;
use warnings;
use Data::Dumper;

my $co = 'b';
my @allcompanies = qw(a b c d);
print Dumper(\@allcompanies);
@allcompanies = grep { $_ ne $co } @allcompanies;
print Dumper(\@allcompanies);

__END__

$VAR1 = [
          'a',
          'b',
          'c',
          'd'
        ];
$VAR1 = [
          'a',
          'c',
          'd'
        ];