If you go to the tab where you can select between economical, fastest route and FSD boost, if you deselect the current option (i.e. if fastest route is selected, click again to deselect it) that should turn off the routing lines. There were a few bug reports during the beta where they couldn't be turned off but hopefully that's been fixed.
No it is not "fixed" - I have been bug-reporting this forever - the galaxy map is a real mess at the moment.
If you do the "click radio button again" to remove the blue jump-line spiderweb, the next time you come back to the galmap the route type is reverted back to economical with the lines displayed. I am fed-up reporting this and getting zero response - oh no, sorry, I did get QA asking for a screenshot - A SCREENSHOT OF THE GALMAP! - Just shows that they have a stock answer to stick on bugs to look as if they are doing something and they apply it without thinking.
What is incredibly annoying about this is that if you turn off the spiderweb with "fastest route" selected, plot your route and then leave the gal map, going back to the galmap for any reason results in your route automatically recalculating to the economical route - goodbye 6 jump trip - hello 19 jumps!
That last point is easily overlooked because the galmap always opens with the left hand tab active, not the last one you had selected - yes I have bug reported that too and didn't even get asked for a screenshot LOL.
[alien]