Found the solution once I stopped panicking!
Have you and the other users the same role? The plugin works on roles, not users!
However if you have admin rights, use the url for the settings to remove settings – wp-admin/options-general.php?page=adminimize-options.
Also you can remove, rename the plugin via FTP access in wp-content/plugins on default. Also you can remove all options in the database, the option entry key mw_adminimize inside the table options.
