Loss of U.S. citizenship is a serious and irrevocable act which deserves your thoughtful consideration.
It is imperative that you fully understand the nature of its consequences prior to requesting a Certificate of Loss of Nationality.
If you decide that this is the course of action you wish to pursue, there are several steps you need to take, including arranging an appointment to come into the Embassy/Consulate General to sign the various documents required to formally renounce to your U.S. citizenship.
Remember that expatriation is a personal right and can never be exercised by another person (including parents and/or legal guardians).
Renunciations cannot be booked as a regular appointment. Please contact the Consular Section at askACS@state.gov in Madrid or email@example.com in Barcelona to book an appointment and receive information explaining the renunciation process. Renunciations require two separate interviews.