BruinLearn by default displays a student's official name based on the information they've provided to the Registrar's Office. This cannot be directly edited by the student. 

Students do have the option of requesting a "preferred name" that may be displayed in certain campus systems such as BruinLearn and MyUCLA. For more info see: https://www.registrar.ucla.edu/Student-Records/Personal-Information/Preferred-First-Name.