I understand what it is you want to achieve, so let me explain. Login (username/password) is optional, but it's either ON or OFF ... You can't have login for one user (with upload/delete capabilities) and at the same time have NO login for other visitors. Multi-user access will be available in a FUTURE release, in which case you can setup public view (no login) and specific users (with login) that have specific capabilities like upload and delete.
There is a simple workaround for this. Let's say you have a PUBLIC Files gallery here:
Create a new dir
filesp (I just added 'p' for 'private' but you can call it anything you want):
filesp dir, drop Files app
index.php and create a file
_filesconfig.php with the following:
'root' => '../files', // point to the public files dir
'storage_path' => '../files/_files', // share cache and config
'username' => 'ali', // login
'password' => 'baba', // login
'allow_upload' => true, // allow upload
'allow_delete' => true, // allow delete
// you can add more options here that apply only for the private /filesp/ dir
Now you can login to /filesp/ in browser, and you will see the content from the public /files/ while having secure access to upload and delete. You can also add other config options to the above, which override config only for the /filesp/ dir.