Based on the level of respect or formality, you can say "Do whatever you want" in Korean in 3 ways:

• Informal: ni-ga won-haneun geon mweo-deunji hae (니가 원하는 건 뭐든지 해)
• Formal: dangsin-i won-haneun geon mueot-i-deunji haseyo (당신이 원하는 건 무엇이든지 하세요), dangsin-i won-haneun geon mueot-i-deunji hasipsiyo (당신이 원하는 건 무엇이든지 하십시요)
• Very Formal: dangsin-ggeseo won-hasineun geot-eun mueot-i-deunji hasipsiyo (당신께서 원하시는 것은 무엇이든지 하십시요)

- you (subjective): ni-ga (니가), ne-ga (네가), dangsin-i (당신이), dansin-ggeseo (당신께서)
- whatever: mueot-i-deunji (무엇이든지), mweo-deunji (뭐든지)
- to want: won-hada (원하다)
- to do: hada (하다)

Please refer to How to pronounce Korean Alphabet for the English pronunciation in this answer.