When's the Right Time For A Father to stop bathing his daughter?

I was listening to the radio yesterday and this topic was discussed. A lot of fathers called into say its their daughter and they'll stop whenever they want. Some mother's claimed that a well trained child would know how to handle that by a particular age while others mothers said the father won't even know how to bath the child so they won't allow it.

Here's my question or questions;
1) At what age should a father stop bathing his daughter and WHY?
2) Being a single dad isn't common in Nigeria but What happens to single fathers?