Zombie Death spawn and de-spawn?

I have created a zombie spawn which spawns a model of the zombie every 5 seconds. However the zombies are breaking up into little Pieces with no Health. The first thing I wanted to tackle was getting them to de-spawn here is what I have for them to do so:

local zombie = script.Parent

if zombie.Humanoid.Health <1 then
    zombie:remove()
end

But they are still not de-spawning.

The second thing is that how do I get the zombie to stay together with full health. here is what I have for the spawning:

while true do

function SpawnZombie()

    local g = game.ServerStorage.Zombie:Clone(1)

    g.Parent = game.Workspace

    g.Humanoid:MoveTo(game.Workspace.ZombieSpawner.Position) --Also assuming that the Humanoid is called Humanoid.

end

wait(5)

SpawnZombie(1)

end

Please help?