Law 27 of the Marleybone Cricket Club’s Laws of Cricket is dedicated to the wicket-keeper. It defines the roles of a keeper, along with emphasis on the position and actions of the keeper on the field. However, nowhere in the law does it state that a wicket-keeper has to be a mandatory part of the playing XI.
Not having a wicket-keeper is a tactic that is rarely employed in professional cricket. The advantage of not having a wicket-keeper is that is allows the fielding side to have an extra fielder that can be positioned at boundaries to stop the flow of runs. However, the biggest disadvantage is that the void behind the batter leaves it open for the batting side to get runs in byes. Thus, when the wicket-keeper is removed, the bowler has to target the stumps.
Only a designated wicket-keeper is allowed to wear protective equipment (helmet, gloves and pads). The removal of a keeper means even his or her helmet is off the field which is a source of five runs for the batting side.
Teams can remove the wicket-keeper during a match. Most of the times this is done when only runs hit in boundaries can help a team secure a match win. For example, if a teams needs 10 runs in 2 balls, a wicket-keeper can be removed and the extra field position can be near the boundary lines to stop a four or six.
While fielding without a wicket-keeper is an unheard tactic seen in professional cricket, it has been reported in lower-tiers.