Here is some code for you...
I like pp in Data::Dump although it is not a core module, it is nice for compact representations of structures.

In order to delete the keys associated with $href1 or $href2 (they are the same), it is necessary to cycle through the keys of %HoH, and compare $href1 against the values of those keys...

#!/usr/bin/perl -w
use strict;
use Data::Dump qw(pp);
use Data::Dumper;

my %HoH = (
   flintstones => {
      lead => "fred",
      pal => "barney",
   },
   jetsons => {
      lead => "george",
      wife => "jane",
      "his boy" => "elroy",
   },
);

my $href1 = \%{$HoH{flintstones}};
my $href2 = $HoH{flintstones};
my $href3 = \%HoH;

#Fails             #yes, indeed this will fail!!
#delete($href1);
#delete($href2);

# These are both references to the sub hash of flintstones...
# sometimes the ability to omit parens in Perl is good thing
# sometime not, here not:
print pp ($href1), "\n"; #{ lead => "fred", pal => "barney" }
print pp ($href2), "\n"; #{ lead => "fred", pal => "barney" }

print "printing HOH...\n";
print pp ($href3), "\n";

#printing HOH...
#{
#  flintstones => { lead => "fred", pal => "barney" },
#  jetsons => { "his boy" => "elroy", lead => "george", wife => "jane"
+ },
#}

foreach my $TV_show (keys %HoH)
{
   delete $HoH{$TV_show} if $HoH{$TV_show} == $href1;
}

print "printing HOH after the delete... flintstones are gone...\n";
print pp ($href3), "\n";  

#printing HOH after the delete... flintstones are gone...
#{
#  jetsons => { "his boy" => "elroy", lead => "george", wife => "jane"
+ },
#}
[download]

Update: it occurred to me, that perhaps you may want "flintstones" to point to an empty hash. in that case:

change:
delete $HoH{$TV_show} if $HoH{$TV_show} == $href1;
to:
$HoH{$TV_show}={} if $HoH{$TV_show} == $href1;
[download]

$HoH{$TV_show}={} means: allocate new hash memory and assign a reference to it to $HoH{$TV_show}