Times Superman has fought and killed Doomsday to my recollection.
1. Infinite Crisis - 2005
2. Superman Doomsday - 2007 movie
3. New Krypton - 2008
4. Reign of Doomsday - 2011
5. Morrison's Superdoom - 2012
6. Superman/Wonder Woman - 2013
7. Doomed - 2014
8. Batman v Superman - 2016
9. Death of Superman - 2018 DCAU
I'm not aware of other instances, but I'm sure they exist. 9 times fighting a one-dimensional plot device (because Doomsday is not a character), over the past 16 years is not a good look. I'm not counting the Paradooms from 2020's Apokolips War. Also, from what I've seen online, Doomsday makes appearances in Scott Snyder's Metal and Death Metal. The point being, just like with the day one origins, we are super-saturated in stories about Doomsday. Enough is enough.