Do the govt tax your CPF when you take it all out?
If you can show ICA a foreign certificate of Citizenship they will allow you to withdraw all of it. It takes six weeks on the ICA side, and they will give you a letter which in turn you must give to CPF for withdrawl, which takes an additional two weeks.
Some countries recognize dual citizenship and some dont. Its important to note that the countries that do not recognize dual will require you to renounce SG before they will grant you Citizenship which places you in a Catch 22 situation as ICA wont allow you to renounce unless you can produce a foreign Citizenship Cert.