Xianhui Chen's group at University of Science and Technology of China observed an electric-field controlled reversible transition from superconductor to ferromagnetic insulator in (Li,Fe)OHFeSe thin flake using the latest SIC-FET gating technique. This work offers a unique platform to study the relationship between superconductivity and ferromagnetism in Fe-based superconductors, and it also demonstrates the superior performance of SIC-FET in regulating the physical properties of layered crystals and its potential applications for multifunctional devices.