my $word = 'abracadabra';
my @list = qw( a b c d e );


my %list = map { $_ => 1 } @list;

foreach (@list) {
   delete $list{$_} if $word =~ s/\Q$_//;
}

@list = keys %list;

print("remaining word: ", $word, "\n");  # raaabra
print("remaining list: ", @list, "\n");  # e