Hydrolyzes the inositol phosphate linkage in proteins anchored by phosphatidylinositol glycans (GPI-anchor) thus releasing these proteins from the membrane. May also cleave GPI anchor intermediates intracellularly. an alpha-D-GlcN-(1->6)-(1,2-diacyl-sn-glycero-3-phospho)-1D-myo-inositol + H2O = 6-(alpha-D-glucosaminyl)-1D-myo-inositol + a 1,2-diacyl-sn-glycero-3-phosphate + H(+) Binds Ca(2+). Belongs to the GPLD1 family.