I know the command list is difficult at best and spread all over the place, but after several days research I come up with the most excellent command structure to create new npc's and sentrys as well as allowing for individual npc removal.

The commands are as follows and should be entered in the order as shown below.

Thename represents what you want to name the npc

/npc create Thename
/trait sentry

--- If you have factions and do not want the npc to target your faction members enter
/sentry ignore add faction:FactionName
To have a sentry target everything enter
/sentry target add entity:all
To equip your npc with armor and weapons have the weapons and inventory in your usable inventory then type
/npc equip
then click the inventory onto the npc
Give the npc a heal rate
/sentry healrate 1
Give the npc armor Strength
/sentry armor 8

Ignore killing of the following types
/sentry ignore add entity:sheep
/sentry ignore add entity:pig
/sentry ignore add entity:cow
/sentry ignore add entity:chicken
/sentry ignore add entity:squid
/sentry ignore add entity:villager

Have the npc ignore other npc's
/sentry ignore add entity:npc

To list all npc's
/npc list

To select npc's you select them by number not by name
/npc select 2
To set a npc as vulnerable or not
/npc vulnerable this is a toggle on or off just read the display after the command to view the status

you can delete individual npc;s but be careful you must have an npc selected to do so
if no npc's are selected you will remove them all.

To select a npc type
/npc select 2 2 being the npc number
to remove a npc after selection type
/npc remove

You can have a npc walk a path but tou will need to remove the npc from any previous used editor.
for example if you just equiped a npc you'll need to exit the equip editor by typing the command again
/npc equip

Now you can use the path editor
/npc path
then walk along and left click where you want the npc to walk and when your finished exit the path editor with /npc path

Both Citizens and Sentry have updates available for 1.6.4

Enjoy