Hi @Braunagel
Welcome to community!
Unfortunately, there isn't a way to remove a single device from your Pandora account, but you can remove all devices using the following steps:
From a web browser, go to pandora.com and log in to your account.
Then click your Profile in the top right corner of the page and select Settings.
Scroll down to the bottom of the page and click on Log out of all other devices.
Enter your password and press Log Out.
If you’ve signed into someone else’s computer, be sure to sign out of your Pandora account once you’re finished.
In the meantime, I've gone ahead and removed your Onkyo device connection from my end. This should log you out when it takes affect, I would give it at least an hour. Then you can try to log back in. If you're still having trouble, I suggest power cycling your Onkyo by unplugging it for at least 5 minutes. Then try once more.
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