～。
That said, could you stop using 'pretty' to describe a guy — it's weird.
Literal
Having-said-that man [to-に] 'pretty' [quot-って] description [topic-は] stop [emph-よな~].
それにしても 'having said that / even so / all the same' is a concessive discourse marker for introducing a comment that stands regardless of what came before. 形容 'description / characterization' is a formal noun for 'a way of describing something.' やめろよな~ is the rough masculine imperative やめろ 'quit it' + よな (affirmative ending) + ~ (trailing vowel) — a complaining, drawn-out plea. The って before 形容 is the casual quotative.