There are many ways to do this in Perl. The following are just a few...

my $string = 'abcdefghijklmn';

# regular expression
$string =~ s/^a//; # chop the first character 'a'
$string =~ s/^.//; # chop the first character

# substring
$string = substr($string, 1); # chop the first charater
$string = substr($string, 3); # chop 3 char's off string

# etc...
[download]

chop and substr would certainly be the fastest way...