CREATE TABLE table_64904 ("School" TEXT, "City" TEXT, "Team Name" TEXT, "County" TEXT, "Year Joined" TEXT, "Year Left" TEXT)

What year did a team from North Dearborn leave?
SELECT "Year Left" FROM table_64904 WHERE "School" = 'north dearborn'
SELECT "Year Left" FROM "table_64904" WHERE "School" = 'north dearborn'