We’re going to leave the very formal goodbyes here and dive into the familiar – or overfamiliar – ones.
Bye… would be “Salut !”
Ciao… would be “Ciao”, “Tchao” (pronounced the same way as Ciao… all’italiana 😉
See ya… would be “À toute” or “À plus” (short for À toute à l’heure and À plus tard)
See ya later… would be “À plus” or “À plus tard !”
So long… would be “À la prochaine” (meaning see you next time)
So long… would be “À la prochaine” (meaning see you next time)
I will not explain the situations when you should or should not use them… it’s about the same in French and English 😉