SELECT "Manner of departure" FROM table_2721 WHERE "Date of vacancy" = '1 December 2009'
Name the manner of departure for 1 december 2009
CREATE TABLE table_2721 (
    "Team" text,
    "Outgoing manager" text,
    "Manner of departure" text,
    "Date of vacancy" text,
    "Replaced by" text,
    "Date of appointment" text
)