Hello,
Sorry, my previous post was lacking a lot of details.
The first thing I should have mentioned is that I don't know this essaywithstart question type.
The only thing I know is that it is not part of standard Moodle so somebody (must probably your administrator) must have installed it.
So can I ask who has installed your Moodle server and who has installed this question type ? It will be a lot easier if the same person uninstall it
The thing to do is also to search if a version of the essaywithstart question type compatible with Moodle 2.3 exists or not, because if you can find one, your administrator will be able to do an upgrade of this plugin rather than to remove it.