The consolidated Maintenance Reminders page is found under Vehicles in your portal.
From this page you can view, edit, delete, and create Maintenance Reminders for any vehicle in your fleet.
Filter by vehicle number from the drop down list at the top of the page.
Add Reminder by clicking

in the upper right. This will prompt the same pop up shown above.
Active reminders will be able to be edited with the

icon.
Completed reminders can be deleted by clicking the

icon under Actions.