There are multiple definitions - click on the translation that matches your context.

demissão means:

demissão

substantivo

partial

sacking

noun

The term sacking is informal in English and is therefore more equivalent in Portuguese to the expressions "mandar embora" or "botar no olho da rua".

(informal) the action of dismissing someone from their job

Around a fifth of cases ended in a sacking or early retirement.

the action of pillaging (=stealing from using violence) a town or a city, especially during times of war or conflict

The sacking of the city was one of the bloodiest events in the country's history.