c:\@Work\Perl\monks>perl -wMstrict -le
"use List::Util qw(max);
 ;;
 my $rx_wordic = qr{ (?<= \\) ABC [^\\]* }xms;
 ;;
 my $maxlen = max map length,
 my @paths = qw(
   C:\somedirectory\anotherDirectory\ABCxyz\myFile.txt
   C:\somedirectory\anotherDirectory\ABCxyz\Logs\myLogs.txt
   C:\somedirectory\anotherDirectory\ABCxyz\Stuff\myStuff.txt
   C:\foo\bar\ABCxyz\baz\boff\ABCxyz\myStuff.txt
   C:\foo\bar\ABCxyz\baz\boff\ABCxyz\xyzzy.zy\a.b\myStuff.txt
   C:\myStuff.txt
   C:\totally\bogus\myStuff.txt
   );
 ;;
 for my $path (@paths) {
   printf qq{%-*s -> }, $maxlen+2, qq{'$path'};
   $path =~ s{ \A .* (?= $rx_wordic) }''xmsg;
   printf qq{%-s \n}, qq{'$path'};
   }
"
'C:\somedirectory\anotherDirectory\ABCxyz\myFile.txt'        -> 'ABCxyz\myFile.txt'
'C:\somedirectory\anotherDirectory\ABCxyz\Logs\myLogs.txt'   -> 'ABCxyz\Logs\myLogs.txt'
'C:\somedirectory\anotherDirectory\ABCxyz\Stuff\myStuff.txt' -> 'ABCxyz\Stuff\myStuff.txt'
'C:\foo\bar\ABCxyz\baz\boff\ABCxyz\myStuff.txt'              -> 'ABCxyz\myStuff.txt'
'C:\foo\bar\ABCxyz\baz\boff\ABCxyz\xyzzy.zy\a.b\myStuff.txt' -> 'ABCxyz\xyzzy.zy\a.b\myStuff.txt'
'C:\myStuff.txt'                                             -> 'C:\myStuff.txt'
'C:\totally\bogus\myStuff.txt'                               -> 'C:\totally\bogus\myStuff.txt'