Lithium deintercalation process and magnetic properties were clarified for lithium nickel oxides with different sample compositions which were characterized by neutron and X-ray diffraction measurements. On deintercalation from the nearly stoichiometric "LiNiO2" (x similar or equal to 0.01 in Li1-x-yNi1+xO2), a monoclinic phase appeared for 0.3 less than or equal to y less than or equal to 0.6. In contrast,no symmetry change from R(3) over barm$ was observed on deintercalation from the non-stoichiometric hosts of 0.05 less than or equal to x. The symmetry change from rhombohedral to monoclinic depends upon the degree of disorder in the host, LiNiO2; the presence of "pillar" Ni ions in the Li layers prevents the lattice distortion, Magnetic behavior was significantly affected by the sample stoichiometry and their interactions were discussed on the basis of weak magnetic-field magnetization measurements.