I have a dual citizenship. Can I leave US for Ghana on Ghana Passport and return from Ghana to US on US passport? or use US passport only.?

US law requires a US citizen to enter and the exit the United States with his US passport. So you'll use your US passport to purchase the ticket, and that passport's number will be entered into the passenger manifest, meaning you'll have to use it again to check in in Ghana.

But you need to differentiate what you do at the airline counter and what you do at passport control.

When you arrive in Ghana, you show your Ghanese passport identifying you as a citizen.

When you leave Ghana, you show your US passport again at the airline counter, and again when arriving in the United States. So the only time you use your Ghanese passport is when interacting with Ghana government officials.

Try it and find out.

one or the other, not both. US Immigration checks your passport when you return to see that it is the same as the one you left on [they check the entry/exit stamps from the other country]. if there is no entry/exit stamp, they start to wonder if you are really a US citizen ...