<p>I have an Ender 5 Pro with a flexible build plate (The factory default one).</p>
<p>There are multiple extremely thin tracks of melted PLA all over it. Too thin to easily peal off when cooled. Thin enough that you can run your finger over them and barely know that they are there.</p>
<p>What is the best way to clean them off other than simply brut forcing them with a scraper and risking damaging the surface.</p>
<p>Rubbing with IPA and a cloth isn't enough.</p>
<p>I have a plastic razor that's normally used for removing vinyl decal from vehicles without scratching the paint, would that be useful, or maybe just scrubbing for an hour with a nail brush?</p>

TL;DR:
Print more PLA on top of them, and pull it off together.
Preparation
First, of course, clean it well with IPA. This will both ensure there's no oil or other material on top of the PLA that will prevent it from bonding well with new PLA, and start to work underneath it to get it loose.
Printing
Then, print! Do a 2- or 3-layer square covering the whole buildplate if you need to, or just smaller ones in the affected areas. They should bond to whatever is there and pull it up when you peel them off.
Prevention
To avoid this happening in the future,
fix your bed leveling
. The type of tracks that are nearly impossible to remove by themselves normally come from printing with the nozzle so low that the material is forced entirely between the texture irregularities of the build surface, with no significant layer on top, and this means your bed is at least a whole layer-height too high relative to the nozzle.