#!/usr/bin/perl -w
use strict;
use Data::Dumper;

sub derefHashTree {
    my( $hv, @keys )= @_;
    my $ref= \$hv;
    for my $key (  @keys  ) {
        $ref= \$$ref->{$key};
    }
    return $ref;
}


my %hash1;
$hash1{key1}{key2}{key3}{A} = "hello";
$hash1{key1}{key2}{key3}{B} = "bye";

my $new_hash = \%hash1;

my @keys= qw( key1 key2 key3 A);

#foreach(  keys %{ derefHashTree($new_hash,@keys) }  ) {
#    print "$_\n";
#}

my $new_ref = derefHashTree($new_hash,@keys);

delete $new_ref;
print Dumper(\%hash1);