Can't uninstall a purchase

Application ID is 3A932C69-022C-443A-FF96-2BA0157DAF00. I want to downgrade to Free plan for this app, because I want to upgrade a plan for another app. The problem is that I have an active purchase that prevents me from downgrading. But when I click Uninstall for that purchase, I keep getting this:

But I’m an admin, so it’s hard for me to believe that I can have no permission for this operation.

Hi, Evgeny.
We are working on your problem, and will fix it asap.

Please, check whether it works now.

Thanks a lot, Oleg!