Which leader of the Puritans during the English Civil War temporarily abolished the monarchy and purged the clergy of Anglican influence?

The answer is Oliver Cromwell (1599-1658), who, as commander of the "New Model Army" against the Royalist forces during the English Civil Wars, signed King Charles I's death warrant, and, after his execution, he eventually became Lord Protector of the Commonwealth of England, Scotland and Ireland, a republic where power was primarily vested in Parliament and a Council of State.

Cromwell was very distrustful of the hierarchy and the formality of the Church of England, and he abolished the bishops and let congregations choose their own ministers.