HPE ProLiant ML350 Gen11

b. Retract and hold the rear retention bracket.
c. Slide out the rear end of the rail to disengage it from the rear rack column.
d. Retract and hold the front retention bracket.
e. Slide out the front end of the rail to disengage it from the front rack column.
HPE ProLiant ML350 Gen11 Server Maintenance and Service Guide 60