|I desist||eu desist||o|
|you/he/she desist(s)||você/ele/ela desist||e|
DESISTIR is usually followed by a de. That’s because when you give up, you usually give up on/of something.
Você desistiu do apartamento? You gave up on the apartment?
Eu desisti da ideia. I gave up on the idea.
Não desista! Don't give up.