With option_toggle you can do it without the need of 2 files. Just 1 macro :
/macro_image "DayJob_XPBoost" "XP Toggle" "option_toggle noxp"
Credit to :
https://forums.homecomingservers.com/topic/13961-the-good-missions-guide-a-heroic-levelling-journey-through-story-arcs
Your XP bar is darker when deactivated below level 50 and you get a message in your chat telling you about the status of the option after clicking it.