your spec if very vague ...

my @array = ('1,2,3','1,2,3,4,5','11,12,13','11,12,13,14,15,16');

@array = do {
    my $last = '';
    reverse grep {
        $last = $_ unless 0 == index $last, $_;
        $last eq $_
    } sort { $b cmp $a } @array;
};
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