Let say you have undeletable file called.pureftpd-upload.446e2f48.15.1dc1.3385a655 in on your site you cantremove, well there is a simple solution to this problem.
You can create a PHP file called something.php, and place this code into it
Now upload something.php to the folder that has the stubbornpureftpd-upload file in it, and change the persimmons of the folder to777 (and something.php) via CHMOD.
Next open something.php in you web browser via your domains URL, as anexample; web page http://www.example.com/path/something.php
Now the file has been deleted.
You MUST delate something.php and return the folder to the originalCHMOD (Normally 644) once you remove the folder for security.
If you have more then one .pureftpd-upload just make additional lines with the file such as