Drop it! (4)
(Other definitions for acid that I've seen before include "So-called drug" , "Sour - sharp" , "- - -drop, sweet" , "Sour - LSD" , "Drug LSD (colloq.)" .)
(Other definitions for let go that I've seen before include "Relax grip and release" , "Release - relax one's grasp" , "Stop holding" , "Give up" , "Release or free" .)