Automatically added to all image fields

This was surprising to me, too. We have a project where we are only using this module for bulk updating old images without alt text initially, so we don't want content editors using the button. I found we can hide the button by adding this to settings.php:

<?php
$config['ai_image_alt_text.settings']['hide_button'] = TRUE;
?>

Note that this only hides the button with display:none. (This option is on the config form for the module, but is only visible if the "Autogenerate on upload" button is checked.)

This solution is good enough for our current project, since we're going to backfill a bunch of missing alt text, and then we can disable the module until we decide about using this going forward. But, ideally, there would be some more flexibility here.