Easily done.
Have two different Menu items
Menu item 1 - Phoca Gallery Categories. When creating it have it accessible by all Registered Users
Menu item 2 - Phoca Gallery User Control Panel. When creating it have it accessible by Special Users
Now go into the php (on your server) and remove the ability for users to upload on the Category page.
the file is: /components/com_phocagallery/views/category/view.html.php
Edit this file.
go to the section that begins with
// - - - - - - - - - - - - - - - -
// TABS
// - - - - - - - - - - - - - - - -
Just prior to this line place the following script:
/* COMMENTED OUT BY ME
Then go to the end of the TABS section. This is just above the following lines (truncated for brevity):
$this->tmpl['dem'] = '<div style="
// ADD STATISTICS
Right above the $this-> line, end your comments. It should read like this at the end
// **** END OF COMMENTED OUT TABS BY Me
*/
$this->tmpl['dem'] = '<div style="text-align:right;color:#ccc;display:block">Powered by <a href="
https://www.phoca.cz/phocagallery">Phoca Gallery</a></div>';
// ADD STATISTICS
By doing this your remove all tabs at the bottom of the category view (including the upload tabs).
Since only you (as a special user) can access the User Control Panel (Menu item 2 above), you are the only one who can upload images from the front end.
voila!