when you delete a word from a level in a course in the browser, it will not appear if you study that level in the browser but is still present in the iOS app.
This seems to be an old bug that has been reported before for the Android app (Deleted words showing up in app).
As this bug creates confusion when learning/reviewing words can you please fix this?
There’s also the draconian solution of deleting the app and re-install it from the App store.
But frankly speaking, the MemRise iOS engineer(s) should really spend some time debugging and fixing their database sync code. It’s extremely fragile and full of bugs.