Why is my plugin still not working?

Alright so this is just supposed to check if I already have supplies in the server and if I do it is to delete them, and then clone more supplies into the server but, It just clones it it doesnt remove them, so say I have supplies in the server then I leave it and save, then I rejoin later I would have two pairs of supplies in the server instead of it deleting the original in the server...

Anyways here is the script, can you tell me whats wrong with it??

location=(game.Workspace) -- This is from a user here thank you guys
children=location:FindFirstChild("Supplies") -- This is from a user here thank you guys
numberofchildren=#children -- This is from a user here thank you guys
supplies = script.Parent.Supplies
if numberofchildren == 1 then
	children:Destroy()
end
wait(.5)
x = supplies:Clone()
x.Parent = game.Workspace

Here's a fixed version of your script.

local Supplies = workspace:FindFirstChild("Supplies")
if #Supplies:GetChildren() > 0 then
    for _, child in pairs(Supplies:GetChildren()) do
        child:Destroy()
    end
end

wait(0.5)

local newSupplies = script.Parent.Supplies:Clone()
newSupplies.Parent = workspace

Here's a rundown of what changed:

I changed this part at the beginning

location=(game.Workspace) -- This is from a user here thank you guys
children=location:FindFirstChild("Supplies") -- This is from a user here thank you guys
numberofchildren=#children -- This is from a user here thank you guys
supplies = script.Parent.Supplies

to the following:

local Supplies = workspace:FindFirstChild("Supplies")

All you really needed here was the "Supplies" object in the Workspace. The rest of the variables were unnecessary. Also, a key thing to note hear is the "local" keyword before the variable name ("Supplies"). For the most part, you should use local variables in your scripts. Among other benefits, local variables can be accessed faster than global variables.

Moving on, I changed this part of your code

if numberofchildren == 1 then
    children:Destroy()
end

to this:

if #Supplies:GetChildren() > 0 then
    for _, child in pairs(Supplies:GetChildren()) do
        child:Destroy()
    end
end

Since we removed some unnecessary variables, we first do a quick check on how many children Supplies has. If it has more than 0 children, we iterate through all of the children within Supplies and destroy them. What you previously tried to do is:

children:Destroy()

The reason that does not work is because GetChildren returns an array of all of the children of an object. You can't destroy an array of an object or call any ROBLOX-related functions on an array. That's why you need to iterate through the array and destroy all of its members.

Finally, I changed this

x = supplies:Clone()
x.Parent = game.Workspace

To this:

local newSupplies = script.Parent.Supplies:Clone()
newSupplies.Parent = workspace

I directly indexed script.Parent.Supplies because we removed the variable earlier. The new method also uses a local, named variable. Like I already mentioned, most of your variables should be local. It's also a good practice for readability to name your variables appropriately, even if they're short-lived.

I hope this helped. Good luck!

Are you sure you turned the plugin on in 'Manage Plugin's'?