Darien Lake removing their Scrambler ride for a lame kiddie ride themed to moose raiding a campground! At least Darien Lake brought back the Scrambler ride in a different area of the park.
That was just last year when Martin's Fantasy Island removed the log flume for a KMG Speed ride that only lasted for a season, but I assumed that the KMG Speed ride was just a temporary "filler" ride for a new ride.
Darien Lake:
* Removing 'Cuda Falls (*takes a big drink*) and replacing it with nothing!
* Removing Nightmare at Phantom Cave for Galaxy Theater and having be SBNO
* Six Flags selling the park resulting in Ride of Steel being stripped from Superman!
Cedar Point
* Demolishing Space Spiral for Gatekepper instead of building said coaster around it!
* Renaming Jr. Gemini to "Wilderness Run"
* Leaving certain rides' special effects to "rot"