As others have mentioned, replaceState in HTML5 can be used to remove the URL fragment.
Here is an example:
// remove fragment as much as it can go without adding an entry in browser history:
window.location.replace("#");
// slice off the remaining '#' in HTML5:
if (typeof window.history.replaceState == 'function') {
history.replaceState({}, '', window.location.href.slice(0, -1));
}