If you have not removed the hoop (or are VERY VERY good at placement) then you should be able to back up the machine and reset to where it quit. If that isn't possible, you can sometimes use an electric mustache trimmer to "shave' the back of the stitches and then scrape on the front with a fingernail or a non-sharp edge, like a credit card. If that won't work or isn't possible, try using your thinnest seam ripper and placing a straight pin under a few stitches at at time and clipping those a few at a time slowly.... OR, why not applique a few cities, stitch them out on another piece of fabric, applique over the offending one and add a few more to make it look intentional?