So this script needs to end the for loop after the calloff = true else statement, after it runs those ending lines, It still loops, How would I fix that from looping after 'else'?

		for racewait = 100, 0, -1 do
		if calloff == false then
			wait(1)
			game.Workspace.StartingLine.Timer.SurfaceGui.Time.Text = "Race time: "..racewait
				for _, Player in pairs(game.Players:GetChildren()) do
        			if Player:IsA("Player") then
            			Player.PlayerGui.MainGui.TimeFrame.Timer.Text = "Race time: "..racewait
        			end
				end
		else
				wait(3)
			game.Workspace.StartingLine.Timer.SurfaceGui.Time.Text = game.Workspace.Positions.First.Value.." has won!"
				for _, Player in pairs(game.Players:GetChildren()) do
	        	if Player:IsA("Player") then
	            Player.PlayerGui.MainGui.TimeFrame.Timer.Text = game.Workspace.Positions.First.Value.." has won!"
			end
				end
				wait(2)
							game.Workspace.StartingLine.Timer.SurfaceGui.Time.Text = game.Workspace.Positions.Second.Value.." came in 2nd"
				for _, Player in pairs(game.Players:GetChildren()) do
	        	if Player:IsA("Player") then
	            Player.PlayerGui.MainGui.TimeFrame.Timer.Text = game.Workspace.Positions.Second.Value.." came in 2nd"
			end
				end
				wait(2)
							game.Workspace.StartingLine.Timer.SurfaceGui.Time.Text = game.Workspace.Positions.Third.Value.." came in 3rd"
				for _, Player in pairs(game.Players:GetChildren()) do
	        	if Player:IsA("Player") then
	            Player.PlayerGui.MainGui.TimeFrame.Timer.Text = game.Workspace.Positions.Third.Value.." came in 3rd"
				wait(2)
			end
		end
	end

Cleaning Up

While it's OK when your code works, it's great when your code works and is elegant. This code can be significantly cleaned up.

First: tab your code correctly. This is so incredibly important!

Next: Use :GetPlayers() instead of :GetChildren(). This also obviates the need for the :IsA("Player") check.

Next: Notice that you have a big chunk of code that's repeated, and no functions! All good code uses functions!

Let's write a function to setText:

-- you can use `workspace` instead of `game.Workspace`

function setText(text)
	workspace.StartingLine.Timer.SurfaceGui.Time.Text = text
	for _, player in pairs(game.Players:GetPlayers()) do
		player.PlayerGui.MainGui.TimeFrame.Timer.Text = text
	end
end

Note that you're putting a lot of trust that this GUI actually exists, which won't be the case for players that are still joining. That's dangerous because you can get errors. You should probably use :FindFirstChild to check:

function setText(text)
	workspace.StartingLine.Timer.SurfaceGui.Time.Text = text
	for _, player in pairs(game.Players:GetPlayers()) do
		local playerGui = player:FindFirstChild("PlayerGui")
		if playerGui then
			local main = playerGui:FindFirstChild("MainGui")
			if main then
				local frame = main:FindFirstChild("TimeFrame")
				if frame and frame:FindFirstChild("Timer") then
					frame.Timer.Text = text
				end
			end
		end
	end
end

This unfortunately gets a little long. If there's only one thing called Timer in the player we can also just use recursive search. That's good in that we can stop caring about how you organize GUIs in the player, but also bad for the same reason.

function setText(text)
	workspace.StartingLine.Timer.SurfaceGui.Time.Text = text
	for _, player in pairs(game.Players:GetPlayers()) do
		local timer = player:FindFirstChild("Timer", true)
		if timer then
			timer.Text = text
		end
	end
end

You can now use this function to make the rest of the code look trivial:

for racewait = 100, 0, -1 do
	if calloff == false then
		wait(1)
		setText("Race time: " .. racewait)
	else
		wait(3)
		setText(workspace.Positions.First.Value .. " has won!")
		wait(2)
		setText(workspace.Positions.Second.Value .. " came in 2nd")
		wait(2)
		setText(workspace.Positions.Third.Value .. " came in 3rd")
	end

Break

If you want to stop a loop, you use the break keyword:

for racewait = 100, 0, -1 do
	if calloff == false then
		wait(1)
		setText("Race time: " .. racewait)
	else
		wait(3)
		setText(workspace.Positions.First.Value .. " has won!")
		wait(2)
		setText(workspace.Positions.Second.Value .. " came in 2nd")
		wait(2)
		setText(workspace.Positions.Third.Value .. " came in 3rd")

		break
	end

	... whatever other stuff
end

The fact that you're using "calloff" suggests that what you're doing is weird. Instead of using calloff, I suggest organizing it like this:

for time = 100, 0, -1 do
	wait(1)
	setText("Race itme:" .. time)
	if (race if over early) then
		break
	end
end
-- Announce winners always at end of race:
setText(workspace.Positions.First.Value .. " has won!")
wait(2)
setText(workspace.Positions.Second.Value .. " came in 2nd")
wait(2)
setText(workspace.Positions.Third.Value .. " came in 3rd")