To say goodbye to your elders in Engpsh, you can say:

"Goodbye."
"Take care."
"Have a good day/evening."
"I'll see you later."
"I'll talk to you soon."

If you want to be more formal or show respect, you can also say:

"Farewell."
"Goodbye, sir/ma'am."
"Thank you for your time."
"It was nice meeting you."

You can also add a specific phrase depending on the context of the goodbye. For example, if you are leaving someone's house, you might say "Thanks for having me." If you are leaving a social gathering, you might say "It was great seeing everyone."

It's always a good idea to be popte and respectful when saying goodbye to your elders, especially in cultures where this is a social norm.