"Hold up! You're double-subscribed"

Hey there @john_bron_tron,

If you're seeing this pop-up after you've cancelled your membership, I'd recommend you get in contact with the live support team so they can review your account and billing details to be sure your membership has been fully cancelled- we aren't able to look into any membership details here on the forums with you since we don't have access to your account detials.

You can contact live support from the help site here so they can look into this with you and see what's causing this pop-up. 

Another admin on a thread of the same topic suggested this, because Live Support couldn't figure it out both times I chatted with them:

This is what you need to do on this one. Contact chat again which I know is kind of a hassle but let them know you need an immediate stop to the subscription. Just canceling won't do much because it will still be there. Let them know you want to have it stopped now so it gets removed from the account now and not when it expires.

I haven't tried to do this yet but I plan to soon.  Hopefully that will help you get a resolution. That alert is extremely annoying.