I cannot stop trials for apps in Confluence, despite being the org admin and currently the only user within my Confluence space. I am also of course the person who installed the apps, so I do not see a reason why I cannot uninstall them. The message I get when trying to stop a trial looks like this:
[App name] is a paid app, so you need to be a member of the site-admins group to stop a trial.
To continue, contact your site administrator for assistance.
I have not changed my user group since starting my Confluence trial, so I am still listed as an org-admin with full control.