How can I kick someone from my account?

I want to share my second account on ps4 ps + but a former friend of mine has my account data and activated primary ps4 and doesn't want to deactivate it, so i can't share it. And then this message comes out.

Doesn't the message say what you have to do?

Yes, but with me the page exists net

https://id.sonyentertainmentnetwork.com/id/management/

Try to change the password via the Ps4 itself, then all other devices would have to be logged off and you can then actually use the primary PlayStation again