I'll answer before I start: " Yes, ok, you can also make users not have profiles that allow them to change the subject or modify it ". And there are very capable plugins, such as Role Manager or Members, to create personalized profiles.
But what if your "client" does not want restrictions ?, if he wants full access except the agreement that has arrived with you, as the designer of the site, from DO NOT TOUCH YOUR SUBJECT, NOR DEACTIVATE IT OR CHANGE THE THEME .
Then it seems to make sense to deactivate any option so that nobody, perhaps save yourself, has access to the options of the topic, even at menu itself.
And you have it.
The user profile " contributor " of WordPress allows you to create entries but, by default, can not upload files with which to illustrate (images for example) your articles.
This can be fixed by several ways, one is to install the plugin Role Manager and assign it this new capacity, or if you think it's too much to install a plugin "just for that", and do not require the rest of the functionality, you can add these lines to the file
If you are still looking for a system with which to control what your WordPress users can or can not do, I have good news.
Adminimize is a megaplugin that allows you to control detail what each user profile can do, see, on the WordPress dashboard.
It's impressive, and it's also translated into Spanish, here I leave some screenshots of the administration screens in case you dare to use it on a specific project . Linked to Role Manager and Register Plus is a really powerful tool.
If you have tried WordPress Beta Testing you will already know some of its virtues.