Renunciation is a voluntary act of relinquishing one's citizenship or nationality. It is the opposite of naturalization, when a person voluntarily acquires a citizenship, and related to denaturalization (where the loss of citizenship is not voluntary, but forced by a state).
Section 349 of the Immigration and Nationality Act (INA) – located in 8 U.S.C. 1481 – deals with the loss of US citizenship through voluntary personal action. Short of committing treason, taking a foreign government post requiring an oath, or pursuing other activities which would cause the Department of State to revoke your citizenship, the way to renounce US citizenship is to make a formal declaration.
You will not be able to make this declaration in the United States - you must go to a U.S. consulate in another country (it should be the country in which you reside legally and where you plan to reside later). You must take an oath of renunciation and hand over your passport. Despite these actions, your renunciation may be denied if the State Department believes you will return to the United States, even for a short visit.
If your renunciation is accepted, your name will be placed in the Federal Registry as a legal notice to anyone, including the Internal Revenue Service (IRS), who might attempt to locate you. it is recommended that you obtain full and permanent residence in another country before renouncing your U.S. citizenship. You should also not that renouncing your citizenship is almost entirely irrevocable and almost impossible to get back. You will also continue to be respinsible for any taxes you owe for upto 10 years, as well as prosecution for any crimes, any debt you have acquired.
You lose the right to reside in the country, you lose the right to obtain federal financial aid if you ever return on a student visa, you will no longer be protected by the Fair Debt Collection Practices Act, and you will also lose the protection of the U.S. Embassy if you run into problems abroad.