Love2d - how do i unload a file.lua - lua

Question

I have a menu screen that has an options button. when I click on this button it load the options.lua file perfectly fine.
love.filesystem.load( "options.lua" )( ) love.load( )
On the option screen I want to add a back button to go back to the main menu. In my head to do this I need to unload the options.lua file.
function love.mousepressed( x, y)
if x > 275 and x < 320 and y > 305 and y < 325 then
end
end

Answer 1

Although Paul's answer is one option, you could approach this differently:
You are thinking about this in a way that will cause you a lot of grief, because in Lua, and many other languages loading files is not meant as a way to run code at variable times. Although this might make you change more code than you want, consider creating a variable for GUI States and only draw what you want if that variable has a certain value. Eg:
Add to your love.load function:
function love.load()
-- Set the gui state to the defualt ( the main menu )
guistate = "menu" -- You probably should use an integer, am using a string for the purpose of clarity.
end
This Goes In the Same Place:
function love.mousepressed( x, y)
if x > 275 and x < 320 and y > 305 and y < 325 then
-- The back button is pressed, change the state to the menu.
guistate = "menu"
end
end
Add to your love.draw function:
function love.draw()
if guistate = "menu" then
-- Draw the stuff for your main menu
elseif guistate = "options" then
-- Draw the stuff for your options menu.
end
end
Extras
Also take a peek at these GUI libraries if you are interested:
Love Frames, and Quickie

Answer 2

There is no way to "unload" that file; you can only negate the effect of its loading. You execute the content of options.lua in that fragment and if it has something like a = 5, to undo this change, you need to save the value of a before executing the code in options.lua and then restore the value later.
Something like this may work for a:
local default = {}
default.a = a -- save the current value of a (if any)
love.filesystem.load( "options.lua" )( ) love.load( )
function love.mousepressed( x, y)
if x > 275 and x < 320 and y > 305 and y < 325 then
a = default.a
end
end
You can go through any other value (for example, have a list of names you want to restore). If you want, you can save all values in the global table and restore them later by iterating over pairs(_G). If you deal with tables, rather than simple values, you'll need to use deep copy to save and restore values.