Not that I'm excusing Lexi of her negligence, she's ultimately the one who should read the rules.. but seriously? Removing an advertising sign, which doesn't require undue delay, to play a shot, saving who knows how many minutes of needing a rules official to make sure they're taking proper relief without incurring a rules violation?
This is just another example of why golf is struggling to gain interest.
If the sign was "removable" without undue delay, why was it deemed immovable?