I see that you are an artist so I'm gonna give you a really neat trick, although using it would mean ditching pencils and paying a little extra for your supplies (but worth it!). It's a matter of supplies but you can get pens with ink that is (very) easily erased by heat. The pens in question (or the only brand I'm aware of anyhow) is called Frixion made by a company called Pilot (So Pilot Frixion pens) these pens cost about 3$ a piece (6$ for two pack) and they come in various different types (Fine, extra fine, ballpoint, point, highlight, LX (luxury), etc) and they erase at around 60°C(140°F) and then they can also reappear at around -10°C(14°F)
If you apply it right you can use it to deliberately erase and even undo your erasing without ever damaging the paper in the slightest. You can "burst" erase an area with a butane lighter then for erasing details you can use a wax sculpting pen. You can see it all in action in my source video.
This might not exactly answer the question for erasing pencil marks without an eraser, but it does provide a completely alternative method. Using this method there are many other ways to get by as well (while un-erasing can pretty much only be achieved via a freezer, erasing can be achieved with all kinds of things around the house, electric heaters or your stovetop for example, a hot running lightbulb, maybe even toss it in the microwave oven to completely wipe it all!)
So I guess this is a way around the problem ever happening, then again the trade-off is that you have to trade your pencil drawing techniques for pen drawing techniques which always end up depending on more than one type of pen (whereas with pencil drawing techniques you can always make do with just one pencil and go all the way with your drawings)