delete an elment of assocaite array

my %a=(a=>1, b=>2);

my $deleteReturn;
my $value;

my $ref=\%a;

#my $deleteReturn=delete $a{"a"};
my $deleteReturn=delete $ref->{"a"};
my $value=$a{"a"};

print "deleteReturn $deleteReturn\n"; #0
print "value $value\n"; #undef