CREATE TABLE table_29715 ("Team" TEXT, "Outgoing manager" TEXT, "Manner of departure" TEXT, "Date of vacancy" TEXT, "Table" TEXT, "Incoming manager" TEXT, "Date of appointment" TEXT)

What is the manner of departure when the date of vacancy is 28 september 2010?
SELECT "Manner of departure" FROM table_29715 WHERE "Date of vacancy" = '28 September 2010'
SELECT "Manner of departure" FROM "table_29715" WHERE "Date of vacancy" = '28 September 2010'