@Amos.Ren - I see from your screenshot, you are currently on a Free Plan team dashboard. For as long as I have been using Miro (over six years), the Trash can has not been an option for Free Plan teams, as noted in the Trash management help center article:

Board owners can, however, load the link of a Free Plan board that was Trashed and restore it within 90 days of deletion. For example, find the board link in your browser history (you can search by board name) and open it to see: