Manual removal and Shrimp if you have a monstrous amount of them to keep the Shrimp fed as for Harq's only eat the tube feet of stars.
BBS though are better choice because:
The Bumble Bee Shrimp will feed upon the tube feet of echinoderms, but do not require them for survival. Offer them pieces of frozen meaty foods such as brine or mysis shrimp, cockle, or small pieces of fish. They should be offered these foods daily.