Formal:
* Até logo: This is the most common and formal way to say goodbye. It means "see you later."
* Até mais: This is also a formal way to say goodbye and means "until later."
* Adeus: This is a more formal and less common way to say goodbye. It means "farewell."
Informal:
* Tchau: This is the most common and informal way to say goodbye.
* Falou: This is another common informal way to say goodbye. It literally means "spoke," but it's used as a casual way to say goodbye.
* Valeu: This is a more casual way to say goodbye and means "thanks."
* Até: This is a very informal way to say goodbye and means "until."
Other options:
* Boa noite: This means "good night" and is used to say goodbye in the evening.
* Bom dia: This means "good morning" and is used to say goodbye in the morning.
* Boa tarde: This means "good afternoon" and is used to say goodbye in the afternoon.
The best way to choose which phrase to use depends on the situation and your relationship with the person you are saying goodbye to.