我无法rm -rf /home/wordpress/testDomain.com从我的 Linux 机器上删除文件。我得到的不是文件被删除，而是错误Operation not permitted。我怎样才能解决这个问题？
$ cd /home/wordpress/testDomain.com/wp-content/plugins/sitepress-multilingual-cms/vendor/otgs
$ sudo rm -f annmanagement
rm: cannot remove 'annmanagement': Operation not permitted
$ ls -al
total 3308
drwxr-xr-x 2 www-data www-data 4096 May 27 13:43 .
drwxr-xr-x 3 www-data www-data 4096 May 27 13:46 ..
-r-------- 1 root root 3375768 Dec 27 2016 annmanagement
$ sudo find . -inum 535255 -exec rm -i {} \;**
rm: remove regular file './annmanagement'? y
rm: cannot remove './annmanagement': Operation …