Untouchable File on Linux Server, Even Though Permission == 777

"Check extended attributes, if applicable:

# lsattr file
----i-------------- file
# chattr -i file

The 'i' bit is 'immutable', meaning it resists all changes."

"My guess is that its one of those annoying .pureftp-upload files. Even if it isn't, there are 2 ways I usually deal with these files.

Use your file manager from within your web hosting control panel (probably CPanel).
Try using PHP (replace the pureftp-upload filename with your filename):

$f = "".pureftp-upload.23kjfvds9osd890235mn"";
unlink($f);

then surround the above code with <?php at the beginning and ?> at the end (code formatting doesn't play nice with php tags)."