A Head Admin is the person who owns and operates a particular MyLeague. They are responsible for the day-to-day operation of the League, and they might be called upon to help resolve disputes in chat or answer questions regarding rules, procedures, etc.
A Head Admin is the owner of their MyLeague. The Head Admin has the final decision for the regular operations of the League. Because the Head Admin is the owner of the League, they are solely responsible for negotiations with other Leagues, managing the League, and managing Revenue Sharing funds. A regular Admin is someone that has been appointed by the Head Admin to assist with the operation of the League.
If you have a problem with an Admin other than the Head Admin, you can contact the Head Admin to discuss the situation and help to resolve the problem. If you have a problem with the Head Admin, then your best recourse is to simply not participate in that particular League. MyLeagues are completely managed by the Head Admin, and MyLeague.com has no involvement in the day-to-day operations.
If you are interested in becoming an Admin on your League, then you will need to contact the Head Admin of the League to inquire about an Admin position.