You need to check with the state where the agency is incorporated. Depending on the State you may be required to have a board with a set number of members. There are some states that allow an individual to be in full control, but not many. Non-profits need to be able to demonstrate that they are accountable and I suppose the idea is that if more than one person is in charge then it is less likely that one person will make decisions that are less than ethical. If you happen to live in a state that allows one person to be the sole propritor of a non-profit, you need to apply for the business showing yourself as the only person, if the business is already established with a board, you will need to check with your state to see how you would change it, it may be as simple as having the by-laws or articles of incorporation changed but it may require more depending on your State's regulations.