Well if we don't focus just on africans then Squanto was a native american who was taken as slave to europe and then made it back to his home. Likewise Enrique of Malacca was a sumatran slave who went all the way around the world with Ferdinand Magellan and then escaped in cebu, the philippines. It's possible if unlikely that he too made it back home given the relatively small distance between cebu and sumatra. Or hell, Robert Adams and James Riley, were american slaves in Morocco who escaped and then crossed the ocean to get back home.

And there were a lot of freed african slaves who were sent back to africa by the slaving powers, too. The americans settled them in liberia, the british in sierra leone and the french in gabon. And the rebel slaves who'd fought the male revolt in brazil were packed back to africa by the brazilian government so they couldn't cause any more trouble in the plantations.

There were even freed african slaves who then travelled back to africa on their own backs. Francisco Félix de Sousa was an ex slave in brazil who later became probably one of the greatest slave traders and gained essentially a royal position as viceroy of the slave trade in the african country of dahomey. And Nii Azumah Nelson probably hired the ship from the english that took his clan from brazil to ghana where they became the Tabom clan.

But none of that is really what you want. What might be an example of that (i.e escaping under their own power and returning home) is Abraham Samuel. Or it might not be.

Samuel was almost certainly a mixed race slave from martinique. he almost certainly escaped from slavery and joined up with an english privateer ship called the John and Rebecca under John Hoar, of Rhode Island. Samuel probably either rebelled when the ship he was on was borded by Hoar's pirates or managed to escape to jamaica himself and joined up with them there.

Samuel was later elected quartermaster and was part of Hoar's crew in a voyage into the indian ocean where the crew was ship wrecked in madagascar.

And this is where it gets complicated. The widow of the king of the Antanosy kingdom then found Samuel and declared that he was her long lost son who was taken away by the french sailor who was his father 20 years earlier and that therefore Samuel was the rightful king of the Antanosy.

Now that is one hell of a coincidence and whie at least some historians seem willing to believe that it was true, and therefore that Samuel was an escaped slave who went all the way back to his home, a bunch more believe that Samuel was born in martinique and the 'long lost son' bit was just a bit of political theatre arranged between him and the queen for mutual gains.

Either way he was king for 8 years before dying in mysterious circumstances.