Hello, I have problem i give my server login info to my admin which is hire for one problem, after i change password but this man again can acces ? how ? Thanks.
No, if you have changed the password he will not be able to. If he creates a user with root privileges on the server, he will be able to even if you change the password. Which user's details did you provide ? Was it the root OR administrator user ?
i change pass but he again can acces in server ''key based'' ? i disable this ''key based'' there some other way someone can acces to server ? Thanks.
He could have backdoored your system. You will need to hire someone to fix the issue. We have some scripts at http://solidshellsecurity.com which could help.
Having the server scanned is the best option I will recommend. Ask your server provider & they will have a check for you as well.