Only one Pope has ever resigned (Celestine V back in 1294), and that was because he never wanted to be Pope in the first place.
More than one pope has, but then we get into arguments about the difference between de facto abdications and formal resignations. From my time with the Jesuits, I recall at least four or five who were in the category of relinquishing power willingly (though perhaps not always eagerly).
All I recall now is one of the 11th century Johns, Benedict the IXth and a later pope who abdicated whilst under the control of a foreign ruler rather than becoming a figurehead.
“Only one Pope has ever resigned (Celestine V back in 1294)...
Yes. He resigned after being arrested and probably murdered. He died in prison.
(From the beginning, he didn’t want to be Pope but was forced into it.
Up until that point, he loved living like a hermit. He abhorred public life.)