Magneto-ionic control of magnetism is a promising route toward the realization of non-volatile memory and memristive devices. Magneto-ionic oxides are particularly interesting for this purpose, exhibiting magnetic switching coupled to resistive switching, with the latter emerging as a perturbation of the oxygen vacancy concentration. Here, we report on electric-field-induced magnetic switching in a La0.7Sr0.3MnO3 (LSMO) thin film. Correlating magnetic and chemical information via photoemission electron microscopy, we show that applying a positive voltage perpendicular to the film surface of LSMO results in the change in the valence of the Mn ions accompanied by a metal-to-insulator transition and a loss of magnetic ordering. Importantly, we demonstrate that the voltage amplitude provides granular control of the phenomena, enabling fine-tuning of the surface electronic structure. Our study provides valuable insight into the switching capabilities of LSMO that can be utilized in magneto-ionic devices.