I need help with a unwanted entity remover. [?]

I am unsure if ClearAllChildren even has a parameter for a part that must be removed.

First, I'll say some things that you're doing incorrect, one being the fact the code doesn't function as you want it to. Now, the second problems you'll stumble upon is your code will continuously run and doesn't stop, I'll use a different loop which will not continue on forever.

A good way to remove the parts is a generic for loop that will check everything in the workspace for the name of "Galalaga" and destroy it. Lets start the loop by making a variable containing everything in the workspace then add it to our loop...

local Collect = game.Workspace:GetChildren()
for _, object in pairs(Collect) do
	
end

Now, object signifies something in the workspace, we want to see if that objects name is "Galalaga".

local Collect = game.Workspace:GetChildren()
for _, object in pairs(Collect) do
	if object.Name == "Galalaga" then
		
	end
end

Now, we need to cause the object to be destroyed.

local Collect = game.Workspace:GetChildren()
for _, object in pairs(Collect) do
	if object.Name == "Galalaga" then
		object:Destroy()
	end
end

Please comment any questions you may have with what I have given... Above is the finished code.