Those prongs are actually studs with a 1/4 in. hex on the end of them. You can remove by using 1/4 in. socket on the bottom of studs. Not sure about belt tension except that if your belt has stretched , you might not need adjustment with a new belt. Hope this helps. Also, by putting cutting deck lever in STOP position will give you the slack needed to get belt off engine pulley.
jeff Seaton
July 2010