To unmount a set of resources on your system, or else all the mounted
resources of a specified file system type, use the umountall
umountall [-F FSType] [-k] [-l | -r]
If you specify a file system type, the command unmounts all mounted resources of the specified file system type. Otherwise, the command unmounts all mounted resources on the system.
For example, you want to unmount all remote file systems currently mounted on your
system. You want to kill all processes that have open files.
Type the following:
umountall -k -r
For umountall, see the mountall(1M) manual page for an explanation of the options accepted by the umountall command.