How come I cannot end active sessions on facebook?

[:)]

Recently my facebook has been getting hacked. Someone is replying and sending messages. Accepting friend requests and doing whatever else to my facebook. I have changed my password multiple times and they are still able to access my account.

My friend told me to go to account settings > security > end all sessions. There are 14 active sessions, some which are my laptop, computer, cellphone etc. But there is a few in california as well. I was able to end all sessions except one from Compton California. How come I cannot end this session? What can I do?

Thanks in advance.