The British ceded their forts by negotiated treaty, not by us shelling them until they left. And they held on to several forts until long after the Treaty of Paris, until Jay's Treaty was signed in 1794.
After the war, they didn't use it for sh*t.
After the war, the fort was in ruins. It was rebuilt, though, and 100 pound Parrott Rifles were installed. During the Spanish-American War, further improvements were made. It did what it was built to do, protect Charleston, and it eventually went the way of scores of other massive coastal fortifications all along the US seaboards and become obsolete.
You and I both know that neither side gave a sh*t about the fort. It was just a toy being contested between two children.