GO:0052846:   inositol-1,5-bisdiphosphate-2,3,4,6-tetrakisphosphate 1-diphosphatase activity
Catalysis of the reaction: 1,5-bisdiphosphoinositol-1D-myo-inositol 2,3,4,6-tetrakisphosphate + H2O = 1-diphospho-1D-myo-inositol 1,2,3,4,6-pentakisphosphate + phosphate + H+.