Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Dear Christopher Jones3,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
Based on your description, I understand that you have a query "Cancel Microsoft Project Plan 3".
Thank you for reaching out to us for this issue; Basically, if this is self-service purchased product, yes both purchaser and admin can cancel the subscription, however, as from your description, you mentioned that you are not seeing it on product list under Billing as the steps as below: in the Microsoft 365 Admin Center **** > Billing > Your products (or Products & services if you use the new admin center) -->Select Filter icon, then select Self-service --> find and click Project Online, then click Cancel subscription to cancel it. You can also choose to take over the control of the subscription from the user, please refer to Manage self-service purchases and trials (for admins) | Microsoft Learn. Please see the screenshot.
Since it is not appearing, could you please suggest the user to check and try cancel from his/her side; you can also disable user to get or get trial again as admin.
If still doesn't work, we recommend that you contact our direct billing Team directly to cancel manually from backend system as link: Find Microsoft 365 for business support phone numbers by country or region - Microsoft 365 admin | Microsoft Learn.
I hope the above information will be helpful. Please feel free to let me know if there are any updates or if I've got you wrong. Glad to assist you. We sincerely appreciate your patience and cooperation. Thanks for your precious time!
Sincerely,
De Paul| Microsoft Community Moderator