These days I would prefer something like:

#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11156715
use warnings;
use Path::Tiny;

sub delete_comments_from_file
  {
  path($_)->edit( sub { s/#.*//g } ) for @_;
  }

my $file = '/tmp/foobar.tmp';

path($file)->spew( <<END );
one # a comment
two no comment
three # more comments;
END

print path($file)->slurp;
print '-' x 50, "\n";

delete_comments_from_file( $file ); # NOTE

print path($file)->slurp;
[download]

Outputs:

one # a comment
two no comment
three # more comments;
--------------------------------------------------
one 
two no comment
three
[download]

There is also a edit_lines() version for 'one-line-at-a-time'.