MCC law for when a player can be declared out bowled
32.1 Out Bowled
32.1.1 The striker is out Bowled if his/her wicket is put down by a ball delivered by the bowler, not being a No ball, even if it first touches the striker’s bat or person
Now to the 'wicket is put down'
29.1 Wicket put down
29.1.1 The wicket is put down if a bail is completely removed from the top of the stumps, or a stump is struck out of the ground,
29.1.1.1 by the ball,
29.1.1.2 by the striker’s bat if held or by any part of the bat that he/she is holding,
29.1.1.3 for the purpose of this law only, by the striker's bat not in hand, or by any part of the bat which has become detached,
29.1.1.4 by the striker’s person or by any part of his/her clothing or equipment becoming detached from his/her person,
29.1.1.5 by a fielder with his/her hand or arm, providing that the ball is held in the hand or hands so used, or in the hand of the arm so used.
29.1.1.6 The wicket is also put down if a fielder strikes or pulls a stump out of the ground in the same manner.
29.1.2 The disturbance of a bail, whether temporary or not, shall not constitute its complete removal from the top of the stumps, but if a bail in falling lodges between two of the stumps this shall be regarded as complete removal.