Hi X Dusatko,

You should be able to link your child's account to yours by using the "Add a child" button on the Parent Dashboard, selecting yes when it asks if your child already has an account, and entering your child's email address. Instructions on linking the account can also be found in this article: https://support.khanacademy.org/hc/en-us/articles/202262994-How-do-I-create-child-accounts-

I hope this helps! Please let me know if you have any further questions.

Hi,

I tied to link my account to child account, but because I used his email as parental, system doesn't allow me to link him with explanation, that this e-mail are not connected to any account. 

BTW, I created a new account for him, under my control, but I would like to clean his older one to avoid issues.

If adding the email address connected to the parent account on the child account's Teachers tab (when the child account is logged in) or adding the email of the parent account on the child account's settings page does not work, then you may have to submit a support ticket so that a member of the support team can manually connect the two accounts.