How to transfer apple account?

I had this apple account for a long time now with about 5 devices on it, it takes up almost all the icloud space and every one of them has who I text and stuff so I don't have any privacy. I made another account but I don't know how to switch apple accounts cuz on my iphone it doesn't let me change the icloud id only the password. I also wondering if you can transfer the photos and contacts too since I don't want to start from scratch but it could be a possibility you can do that. I'm not too sure please answer and help me out.

You can't transfer content from one account to another. And yes you can sign out of iCloud it's just that you need the password for it.

Sign out of iCloud and then Sign in to another account.