How come I cannot end active sessions on facebook?

[Barbara]

the hacker is using it so you cant delete it, you should change your primary mail and password.
1. Goto 'Account Settings' it is in the upper-right corner near your profile icon.

2. There will be a section called 'Primary E-mail Address', click the option called 'Edit' which is adjacent it.

3. There will be an option called 'Add another E-mail'. Click it then you can enter a secondary email account.
4. Select the email you just added as your primary email address. DONE.

Then open the mail which you provide as primary mail and confirm it.