https://messages.google.com/disable-chat
This is similar to Apple's iMessage deregistration page.[1]
Google has been funneling RCS messages through its own servers to bypass wireless carriers, which were slow or unwilling to directly support RCS.[2] Unfortunately, this has centralized RCS communications through Google and allowed Google to make end-to-end encryption available to RCS users as a proprietary extension that Google never contributed back to the RCS Universal Profile specification.[3]
For RCS on Android to be decentralized again, your wireless carrier would need to support RCS on the network level and Android would also need to implement RCS in a way that does not require interaction with Google servers. This would make deregistration unnecessary.
[1] https://selfsolve.apple.com/deregister-imessage/
[2] https://www.extremetech.com/mobile/302020-google-will-bypass...
[3] https://appleinsider.com/articles/23/11/16/apples-flavor-of-...