Abdication
In the past, there has been a British monarch who gave up the throne altogether as well. It is not common at all, however. Edward VIII was the only king who abdicated of his own will. In 1936, he made the decision due to the opposition to his union with an American divorcee called Wallis Simpson.
Other Abdications
Rulers before him abdicated with, let us say, some persuasion. Richard II abdicated when Henry Bolingbroke, his cousin, stole power in his absence. In 1688, James II ran away from England during the revolution. At the time, it was not certain if he abdicated or forfeited. They only knew that he was out.