Hi there, beyondbookeeping.
I'd be happy to help you correct this problem.
When you try to separate the incorrect sub-account from the parent account, did you choose a different parent account? If so, then that would be the reason why you're getting the error.
To fix this, you just need to uncheck the Is sub-account checkbox to separate the sub-account and click Save and Close. Then, if you need to transfer it to a different parent account, edit it again and select the Is sub-account checkbox, then hit Save and Close.
That should do it. Please keep in touch if you need further assistance with this, or if there's anything else I can do for you. Have a good one!
