Hey, wait !! . I don't think it is necessary to remove the CA. . Just add a little bit more to fill the offending scratch.
The objectionable scratch is circumferential and will most likely fill up nicely by doing a couple more applications of CA.
Also, you need to think about how that circumferential scratch got there !! . In my opinion, it's likely from circumferential sanding !!
I do all my CA sanding with the lathe off, and doing all sanding strokes lengthwise. . I never do any sanding of CA circumferentially.
It helps if you can get your CA application technique up to the point where there are minimal lumps and bumps on the surface.
A few streaks are OK because they will sand out with your longitudinal sanding.
My CA application technique is now fairly good, and I can usually start my longitudinal sanding with 320 grit, going up to 1500 grit.
I turn the lathe headstock by hand and count the strokes, doing first of all about 100 strokes for the coarser grit and working down to about 50 strokes with the fine grit. . For one revolution of the blank, it works out to about 10 longitunidal strokes, applying the sanding pressure mainly with the cushion of my thumb.
I think we all must be OCD ! . I am very fussy about the sanding process. . With the coarser grit (320 grit), I like to get the blank very smooth with no shiny spots showing. . If there are any shiny spots, they indicate surface irregularities (ups and downs) and I don't want any of those. . Of course, you never want to sand through the CA down to the wood. . If you do, then you might have to take off the CA and start again. . But that is a very messy job and you want to avoid it.
After the fine sanding, I use a Mequiar's coarse automotive "cut polish" .... again using longitudinal strokes. . I then progress to Novus 3, then Novus 2, and finally PlastX. . Things are now looking pretty nice with a glossy shine all over. . I don't use any rags or paper during all this polishing, just the fingers and thumb of my right hand as I turn the headstock with my left.