Germanium Telluride (GeTe), identified as a ferroelectric Rashba semiconductor, is a promising candidate for novel electronic devices in computing and memory applications. However, its ferroelectric switching in a microscopic scale remains to be understood. Here, we propose that the migration of a domain wall can be the mechanism that mediates the ferroelectric switching. By employing ab initio methods, such a mechanism is characterized by an energy barrier of 66.8 meV/nm^{2}, in a suitable range for retention and switchability. In accompanying the domain wall migration, the net Rashba effect is tunable, as it is a result of competition between layers with opposite electric polarization. These results shed light on the ferroelectric switching mechanism in GeTe, paving stones for the design of potential GeTe-based devices.