use File::Spec::Functions qw( catfile );

my $dir = ...;
opendir(my $dh, $dir_name)
   or die("Unable to list contents of dir \"$dir_name\": $!\n");

while (defined(my $file_name = readdir($dh))) {
   my $full_name = catpath($dir_name, $file_name);
   next unless -f $full_name;
   unlink($full_name)
      or warn("Unable to delete file \"$full_name\": $!\n");
}