Description for Brazilian nationals, it might be different for other countries.

Steps:

1. Go to https://registrocivil.org.br/birth-certificate and request a updated digital birth certificate
2. Apostile, in Dutch, the document that you have received during the naturalization ceremony, which confirms that you are Dutch citizen. You bring the document to the court, and you get it back in the same time. You can find here a list of the courts in the Netherlands that can apostille the document. No appointment is needed. *Note that some courts there don't do this service, so they take your document send to one that does, and get document back later. If you go straight to the one that does it, you get the document back immediately. Courts that don't do it:
   1. Almere (De Diagonaal 37)
3. Translate the document to Portuguese with a sworn public translator registered with the Boards of Trade of the Brazilian States
4. Go to Sei and request a Solicitação de Perda de Nacionalidade
5. Upload all documents required and fill the form there
6. You will receive an email confirming that it was posted on the Diário Oficial da União after a few weeks
7. Make an appointment on Brazilian embassy website or just go there, bring your passport and the page of the Diário Oficial da União (can be on your device) to get a certificate that you have lost you citizenship
8. Legalize the document received from the Brazilian embassy on Ministry of Foreign Affairs
9. When you get the letter requesting to lose your citizenship from IND, you send this Legalized document to them, you can also upload it online.