Answer:
It's always difficult to translate expressions and idioms.
Here's a better, and more accurate answer:
'Good riddance' is an expression of pleasure on being rid of some annoyance - usually an individual.
So, in the context of "Good-bye and good riddance" you could say (in Swedish) "Adjö. Skönt att bli av med dig" - if you are referring to a person
Or "Skönt att bli av med skräpet" - if you are trying to say 'good riddance to bad rubbish.'
---Original Answer---
Adjö