Use the umount command to unmount a currently mounted file system.
See the umount_vxfs
(1M) manual page.
To unmount a file system
umount [-V vxfs] [generic_options] [-o [force]] {special|mount_point}
umount [generic_options] [-o [force]] {special|mount_point}
Specify the file system to be unmounted as a mount_point or special. special is the VxFS block special device on which the file system resides.