my @keep;
for (my $i = 0; $i < @array; $i++) {
    my $_ = $array[$i];
    push @keep, $i unless $_ eq 'hello';
}
@array = @array[@keep];

##</code><code>##

for (my $i = @array; $i--;) {
    splice @array, $i, 1 if $array[$i] eq 'hello';
}