Much like with an order, there is no way to delete a marketplace, channel, or store from your account. However, you can make them inactive, which will essentially hide them from view within the app.
Inactivate a Marketplace, Selling Channel, or Store
1. Go to your Account Settings (the wrench icon in the upper right).
2. Select Selling Channels and then Store Setup from the left-hand sidebar.
3. Click on Edit for the store you wish to mark as inactive.
4. Uncheck the Is Active? checkbox under the store's logo.
5. Click the Save Changes button.
This store, and all of its orders will now be hidden from view.
As with any canceled orders, inactive stores' data will not be included in any reporting.
IMPORTANT: To make a store active again, follow these instructions again, but check the box this time.