Belt tension is released via the torx bolt that secures the tensioner pulley to the tensioner assembly. To do this you use a ratchet and turn clockwise as if tightening the bolt. The longer bolt pictured is a mounting bolt for the upper pivot point to the engine block. The longer bolt should only be removed once a belt has been removed from the vehicle. The tensioner pulley bolt on it's own is p/n 07129905534 and the longer mounting bolt is p/n 07119904532. Both are listed on our site and can be found by searching the part number.