If the project lends itself to it, cover up the areas that have already carved with a white box. Or I have jacked me speeds way up until it catches up with were it stopped. Been over a year since that happened to me.
Yes, gcode can be edited to remove previously carved code.
If you homed your machine ($H) before jogging to your work zero point, you cen re-home and use previous work zero as its stored as an offset from machine home position.
In Easel you can choose to export the gcode file, this can be opened in any text editor program and edited there. I do not have experience with editing gcode myself so cannot comment further.
Once edited, save the file and in Easel choose import gcode.
A prerequisite is that you have a way to restore your reference points (work zero)
In Easel, click on machine at the top of the page and then click on advanced. Then click on generate gcode and finally export Gcode. In microsoft wordpad you can open the gcode file from where you saved it and remove the text you don’t want.