Take a look at support.xbox.com/.../online-safety
What settings are you trying to change.
Parental control can not be removed until the account is of legal age in the region it was created.
Banana? + mEouse? = Squirrl!
If it is issues with Demos and trailers are restricted on child accounts if they are m rated or rp
Due to international laws on advertising
As stated above you cannot remove parental restrictions till the account turns the legal age of the region
If it is not demos or betas or trailers then
Have you tried redownloading the profile?