To turn off assignment settings so parents cannot see their child's assignments:
  1. Go to Core > Security >  Roles > Parent  > Manage Task 
  2. Unmark all assignment and assessment tasks in the Parent Role
User-added image
  1. In Academics >  Grades > Grading Setup > Assignment Settings, make sure the Assignment Settings are turned off for the parent role, as this will override any User settings
User-added image