ktstudios on "How do I deactivate the All Authors Page plugin?"

There is a typo that generates the error. You can edit the plugin file allauthorpage.php at line 412.

The line reads:
delete_options($this->_name.'_show_email');

It should be:
delete_option($this->_name.'_show_email');

Just remove the 's' from the delete_options function call.