Ar-Pharazôn, as told in the 'Downfall' or
Akallabêth conquered a terrified
Sauron's subjects, not Sauron. Sauron's personal surrender was voluntary and cunning: he got free transport to
Númenor! He naturally had
the One Ring, and so very soon dominated the wills of most Númenoreans. (I do not think Ar-Pharazôn knew anything about the One Ring...)...Sauron was first defeated by a 'miracle': a direct action of
God the Creator, changing the fashion of the world, when appealed to by
Manwë: see III p. 317. Though reduced to 'a spirit of hatred borne on a dark wind', I do not think one need boggle at this spirit carrying off the One Ring, upon which his power of dominating minds now largely depended. That Sauron was not himself destroyed in the anger of
the One is not my fault: the problem of
evil, and its apparent toleration, is a permanent one for all who concern themselves with our world. The indestructibility of
spirits with free wills, even by the Creator of them, is also an inevitable feature, if one either believes in their existence, or feigns it in a story.