In your AppScenic Account, click on My Stores and then on My Stores.
Now find the store you want to delete and click on the ACTIONS button on the other side of that store.
Choose Disconnect, in case you didn't do that already, confirm your update and click on SAVE. This will change the STATUS of your store to OFFLINE.
Depending on your platform's store, you will need to wait a bit until you can also delete it from AppScenic.
Once that's possible, you have to click again on the ACTIONS button, choose Delete and then SAVE.
And now your store is disconnected from AppScenic.