Prevent deleting files

[scorpoin]

Greetings,

I just installed a fresh freenas and created a pool and a shared folder named it public, I set user to nobody and group wheel . I did little modification in permission set it to advance as below

Code:

Read Data
Write Data
Append Data
Read Named Attributes
Write Named Attributes
Execute
Read ACL

Now my question is anonymouse user can create folder but can not delete the folder so far so good but when a user copy any file I.E text or exe in that folder he/she can delete those files except folder. How do I prevent user not to delete files as well.