Hi,
no problem :-) And thanks for the clarification.
The best way for this would then be to take away all rights ("capabilities" in WordPress lingo) that are related to TablePress from "Author" users. To do that, please temporarily install the "Members" plugin from http://wordpress.org/extend/plugins/members/
Its "Role Editor" module allows you to strip all capabilities that start with "tablepress_", which effectively takes the right to access and use TablePress for all authors.
After doing this, you can uninstall Members again.
Regards,
Tobias