Cannot cancel a subscription

I'm sad to know that you're canceling your client's QuickBooks Online (QBO) subscription, 

Nonetheless, I'm here to help and make the process easy for you. 

To begin with, I suggest logging out and logging back in to your client's QuickBooks Online (QBO) account to refresh the system. Then, cancel the account again.

If this is not the case, I propose accessing your client's account in a private or incognito window. This way, we can check if this is a browser's cache issue.

The browser uses cache data to load web pages faster the next time you visit a page. However, too much of it causes issues that can affect the performance of your client's account. Using an incognito window helps us verify this matter as this doesn't save any data files. 

To open a private window, you can refer to these keyboard shortcuts: 

• Ctrl + Shift + N (Google Chrome browser)
• Ctrl + Shift + P (Mozilla Firefox & Microsoft Edge browsers)
• Command + Shift + N (Safari browser)

If you’re able to cancel your client's account, I’d suggest clearing your regular browser's cache to optimize your browser. If the issue remains, I recommend using other supported browsers. This way, we can check if this is a browser-integrated issue. 

In case your client's wants to reactivate their account, you can share with them this article that can guide them through the process: How to resubscribe or reactivate QuickBooks Online.

If there's anything else you need help with your client's QuickBooks, you can always tag me in your reply. I'm always here to back you up!