How to remove words from a string?

I am trying to figure out how to remove a word from string. I tried using string.sub but don't know what to do from there.

local String = "Buy Model"

if string.sub(String, 1, 4) == "Buy " then 
	--I know you can do String = string.sub(String, 5, 8) but there is multiple strings I want to remove "Buy " from
end

I found one way to do it:

local String = "Buy Model"

if string.sub(String, 1, 4) == "Buy " then 
	local stringLength = string.len(String)
	String = string.sub(String, 5, stringLength)
	print(String) -- prints 'Model'
end