Use UNIX utils if you want to, but I prefer perl. Here's a code snippet:

#!/usr/bin/perl -w

use strict;
use File::Find;

my($dir)  = shift;
my($days) = 14;

die "Invalid dir" unless (-d $dir);

&find(\&wanted, "$dir");

sub wanted {
  -f && (int(-C _) < $days) && print "$File::Find::name\n";
}
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Of course, this will just print which files it would delete, not actually delete them. That's left to the reader. :)