Big decision but process has not changed. Schedule an appointment with US citizens services at the US Embassy or walk in if allowed and simply tell them you want to renounce your US citizenship. They'll let you fill the appropriate forms DS-4079 and pay the renounciation fee, take oath.
Useful resources.
https://travel.state.gov/content/travel/en/legal/travel-legal-considerations/us-citizenship/Relinquishing-US-Nationality-Abroad.html
https://travel.state.gov/content/travel/en/legal/travel-legal-considerations/us-citizenship/Renunciaton-USCitizenship-persons-claiming-right-residence.html
https://www.usa.gov/renounce-lose-citizenship
https://uk.usembassy.gov/u-s-citizen-services/citizenship/loss-of-u-s-citizenship-i-e-expatriation/
https://www.ait.org.tw/renounce-u-s-citizenship/