My book said:
For convenience, we say that the electric potential energy of a neutral object is zero. In fact, the epe of a neutral atom is not zero but negative. A lot of energy is needed to remove an electron, known as ionization. Therefore, when a charged object is discharged, epe becomes more negative. In other words, a neutral object has a very large negative electrical
potential energy.
But I think that when an excessive negatively charged sphere is discharged. Electrons are taken out from the object. Positive work done is needed as the nucleus is positive and exerts an attractive force to the electrons. So the object should be more positive. Then why " when a charged object is discharged, epe becomes more negative. "?