I just looked up that particular motherboard, and it looks a bit finicky to grab the CPU after install, so I have no advice other than trying again, maybe you can grab it by the heatsink top?
I used this video for reference, so not sure if your CPU looks exactly like that: https://youtu.be/kbUCZgC2CGE
And this video shows removal: https://youtu.be/cltgIYiGtWY
I wouldn’t want to breathe H2O2 vapor.
But H2O2, over time, dissolves into H2O + O2, so washing/rinsing with H2O2 is fine, just let it air out for a few days afterwards to be safe.
For thorough cleaning, is running it with H2O2 outside an option?
Disclaimer: I’m not a chemist. At least mot to you. I’m a random dork on the internet who could be trying to kill you for the fun of ut. Anything I say should be treated as such.