The command line tool smbumount is a user tool to allow normal users to unmount samba shares that they have earlier mounted using smbmount. Normally only the root user can mount or unmount resources, however to improve the user experience some tools have been written allowing users to perform these operations themselves. This also improves the security of the system as an administrator password is not required for mounting shares that will be used only by one user.
mount-point: The directory that the user previously mounted an smb share on with smbmount.
The smbumount command is part of the smbfs package. Installing using apt on Ubuntu can be done with the command sudo apt-get install smbfs, alternatively the package can be installed via your distribution's package manager.