Mount remote folder:

$sudo sshfs -o allow_other,defer_permissions user@remotehost:/home/huang/foldertomount /mnt/localfolder

Unmount remote folder:

 $ sudo diskutil unmount /mnt/localfolder

If Unmount failed for /mnt/localfolder:

 $ sudo lsof | grep localfolder

and kill the process using localfolder