How does one exchange restricted currencies?

I just traveled to Morocco which uses the Dirham as its currency and now that I have returned to the USA I am looking for a way to convert my Dirhams to Dollars, but I read that the Dirham is a restricted currency and as such will be difficult to exchange outside the country. Any ideas would be appreciated.How does one exchange restricted currencies?go to central bank and ask them.Normally they deal in all sort of currencies.