There is no answer for a general "some country," each country has its own laws.
In the US, you need to meet with the State Department (possibly through an embassy) which takes care of the legal aspects of renouncing your citizenship. The second part is filling out all of the forms and paying all of taxes required by the IRS (which is not insignificant). It is not cheap to renounce your citizenship (unless you don't really have anything).
In the US, you need to meet with the State Department (possibly through an embassy) which takes care of the legal aspects of renouncing your citizenship. The second part is filling out all of the forms and paying all of taxes required by the IRS (which is not insignificant). It is not cheap to renounce your citizenship (unless you don't really have anything).