I am currently running SpamSieve on my MacBook Pro but this is not always switched on, especially when i am travelling and then I get loads of unnecessary spam in my inbox on my IOS devices.
I also have a Mac Mini that is always on, so I am considering moving SpamSieve from my MacBook Pro to my Mac Mini but if possible would like to take most of its ‘learning’ with me!
You can just uninstall it. If your Mail rules are syncing via iCloud, just uncheck the SpamSieve rule on the MacBook Pro, rather than deleting it, so that it doesn’t get deleted on your other Mac.