The control and monitoring of the polarization of terahertz radiation are of interest for numerous applications. Here we present a simple controllable THz emitter with a small coercive magnetic field. It is based on a Co/WS2/silicon structure, in which the presence of uniaxial magnetic anisotropy caused by mechanical stress in a ferromagnetic film was found. Our results show that a ferromagnet/semiconductor emitter can become a technologically simple device for terahertz spintronics.