Nicely thorough. Along the lines of my other reply,

use File::Spec::Functions qw( splitpath splitdir catpath catdir );

sub unmkpath {
    my ( $path ) = @_;

    my ( $vol, @dir ) = do {
        my ( $vol, $dirs ) = splitpath( $path, 1 );
        ( $vol, splitdir $dirs );
    };

    pop @dir while @dir and rmdir catpath $vol, catdir( @dir ), '';
}
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Makeshifts last the longest.