There is an active profile manager on your father's profile. Do you know him or know who he is? Maybe he is a relative? Regardless, you will need to contact him, explain your relationship to your father and ask to be added to the Trusted List or added as another profile manager. Explain that you want to remove the private children and work on his profile.
If you do not receive a reply in a reasonable period of time - a couple of weeks, then file "unresponsive profile manager" form.