use Data::Dump;
%f = 1..8;
dd\%f;
delete @f{1..4};
dd\%f;
$f=\%f;
delete @{$f}{1..8};
dd $f;
__END__
{ 1 => 2, 3 => 4, 5 => 6, 7 => 8 }
{ 5 => 6, 7 => 8 }
{}