This my $location_hash = get_location(\*ZIPS);

and this my $cat_hash = get_categories (\*SICS); are already a hash references, so you don't need to use backslashes

here catch_error(\*LOGS, \$page, $location_hash, $cat_hash );.

Then, you just name the references inside the sub and use them in exactly the same way as you have in the code outside the sub.

sub catch_error{
   my ($fh, $str, $location_hash, $cat_hash ) = @_;   
   ...
   delete $location_hash->{'the key'};
   ...
}
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