brainwashing
process in which a group or individual "systematically uses unethically manipulative methods to persuade others to conform to the wishes of the manipulator(s), often to the detriment of the person being manipulated"
en-GB/ˈbɹeɪnwɒʃɪŋ/
en-US/ˈbɹeɪnˌwɑʃɪŋ/