Sometimes, the app's feed updates automation may miss a few deleted products during updates. When deleted products still show in your feed, one option would be to head over to your products page and manually delete the product.
After, hit the 'update all feeds' button to reflect your changes in the feed.
Another option will be to use the reset products method. Please see how to reset your products here
If these options do not remove your deleted products, please let us know.