All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
Tattooing is forbidden, and those who practice tattooing and those who get themselves tattooed are cursed. Imaam Al-Bukhari reported that the Prophet cursed those ladies who practice tattooing and those who get themselves tattooed. So whoever has done this has to repent to Allaah and remove the tattoos if possible whether by undergoing an operation or by other means as long as he is not greatly harmed, otherwise repentance is sufficient and he will not be held accountable for the trace of tattoos.
Finally, it should be noted that tattoos do not invalidate belief completely to an extent to render the tattooed person a non-Muslim but it may decrease his belief if he does not repent.
Allaah knows best.