The trick is to split the letters with diacritical marks into the base letter and the mark, which Unicode::Normalize does with the NFD function. Then the regex /\pM/ identifies marking characters (see perlunicode).

use strict;
use warnings;

use utf8;

use Unicode::Normalize;

my $s = "söme stüff\n";
$s = NFD($s);

$s =~ s/\pM//g;
print $s;
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Depending on the application, the NFKD might or might not be more appropriate than NFD.

The code snippet above removes all marking characters, not just diacritical marks. You can change that by removing only \x{308}. The following code strips the diacritical mark, but leaves the accents:

use strict;
use warnings;

use utf8;

use Unicode::Normalize;
binmode STDOUT, ':utf8';

my $s = "söme stüff with áccènts\n";
$s = NFD($s);

$s =~ s/\x{308}//g;
$s = NFC($s);
print $s;
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