Fix this so the descendants can't collide with anything and explain what I did wrong so I learn from it

Title explains

local PhysicsService = game:GetService("PhysicsService")
PhysicsService:CreateCollisionGroup("NoCollide")
PhysicsService:CollisionGroupSetCollidable("NoCollide", "NoCollide", true)
for _,v in pairs(script.Parent:GetDescendants()) do
	if v:IsA("BasePart") then
		PhysicsService:SetPartCollisionGroup(v, "NoCollide")
	end
end

Set that to false

PhysicsService:CollisionGroupSetCollidable("NoCollide", "NoCollide", false)

Though if you mean, collide with nothing at all, you need to do a bit more. This turns off all collisions from one group with all groups.

local PhysicsService = game:GetService("PhysicsService")
PhysicsService:CreateCollisionGroup("NoCollide")

for _, group in pairs(PhysicsService:GetCollisionGroups()) do
    PhysicsService:CollisionGroupSetCollidable("NoCollide", group, false)
end

for _,v in pairs(script.Parent:GetDescendants()) do
	if v:IsA("BasePart") then
		PhysicsService:SetPartCollisionGroup(v, "NoCollide")
	end
end

Throw this back in there somewhere if you want it to collide with things in its own group though

PhysicsService:CollisionGroupSetCollidable("NoCollide", "NoCollide", true)

so you wouldn’t be able to collide with anything in game but still be able to walk on things?

I believe walking requires collisions.

Didn’t work. Its essentially noclip