- When the object is removed, the volume that the object occupied will fill with fluid.
- This volume of fluid must be supported by the pressure of the surrounding liquid since fluid cannot support itself.
- When no object is present, the net upward force on this volume of fluid must equal to its weight, i.e. the weight of the fluid displaced.
- When the object is present, this same upward force will act on the object.
More info on https://physics.tutorvista.com/fluid-dynamics/buoyancy.html