The integration can be cut off at any time within Seller Central as follows:
1. Go to Seller Central -> Settings > User Permissions
2. Click on "Visit Manage your Apps"
3. Click on "Disable" as shown below
For long-term customers the developer name may still be called "Marketplace Analytics", which was our previous brand before Sellics.
Only Account Owners see this Option
Please note: in most cases only the account owners are able to disable API connections.