> I used to be able to enlarge a jpg to view pixels and change or remove colors by selecting individual pixels. Is that still possible?
Sure, just zoom in like before (Z key, and Shift-Z to zoom out).
> Or is there an eraser tool on this version?
No. But maybe you could try blurring it away if the line isn't too contrasty: Make a freehand selection (Alt-Mouse), then Image | Filter | Select Filter | Blur. A dedicated painting or photo editing program probably has better suited tools for this job though.