Karen,
We should not use regular pencils as they contain graphite that is waxy and difficult to remove. Suggest you use the blue markers next time as they disappear with a spritz of water.
I believe Fons and Porter had a solution for this removal problem. Don't quote me on this, but I recall 1T of WHITE kitchen dish detergent, 1T of alcohol and 3T of water. Mix together and use a Qtip and stroke the lines until they disappear. Then use a Qtip with just water to rinse. -- Please try this on a scrap before using it on your project since I am not sure of the exact formula.
Please advise the rest of us about your results. Suzanne