Which one of the following adjectives is the right one to describe someone who has just stepped down as a manager?
- "Resigned manager"
- "Stepped-down manager"
Which one of the following adjectives is the right one to describe someone who has just stepped down as a manager?
Neither resigned nor stepped-down is an adjective. And neither is used attributively (before a noun phrase being modified). As to choosing between
the manager who resigned
and
the manager who stepped down,
the choice depends on context and precise meaning. Resign means leave an organization’s employment altogether, whereas step down can mean that, but can also mean leave one position in favor of another one, typically of lower rank.
If one doesn’t choose to make that distinction, then, as @Yosef Baskin has commented, ex-manager is fine.