This change will not affect your account. When a customer account is linked or unlinked from a client manager account, the account retains its history of campaigns and still offering access to all features of the AdWords program. To change the administrator, must have e-mail address and password necessary to access your account. You have access to unlink your account from the account of a client manager, while he and his representative of customer service can only link accounts.
To unlink your account from the account of a client manager, please follow these steps: