How to secure forum from third party

[bogze]

A forum was designed by an expert who can really design with smf 2.0 very well, i advised a friend to patronize the guru. he also requested if there is a way to have full control of the forum after completion and transfer of ownership. I told him to change the password and other information from the admin. control but he still need assurance that the forum developer expert will not gain access to it any other time. Though the domain host was sent to the guru to upload the forum after completion, which shows that he has everything to himself. please what are the other areas to get ownership from this expert so that my friend can have confidence of full control of his forum.