@ary = qw( 0 1 5 5 5 0 5 5 5 1 0 );

$" = "~";

print "@ary\n";

for my $i ( 0 .. $#ary ) {
    # undefine bad element
    undef $ary[$i] if $ary[$i] == 5;
}

# now remove undefined elements
@ary = grep{ defined }@ary;

print "@ary\n";