I use the art gum eraser over ink. They're the brown ones that kind of crumble as you erase. I do use a light, light touch with them. I then scan them with the settings set to Black and White. That way even if there is a tad of pencil left over it will be light enough not to be picked up by the scanner. Fun story I heard from comic book artist Stephen R. Bissette. He joked about that people don't realize how much of a horror show a page looks physically when he's done with it. Thick blobs of white out, eraser skids, even cutting out parts of the Bristol board and replacing it with a clean cut out. Doesn't matter because none of that gets picked up in the printing process.

Look its my sketch of today i dont errise any pencil but they dont seen when ink

Another tip: when you have a pencil sketch, use a kneaded eraser to lighten it before inking. There will still be marks, visible enough for you to ink over, but once you ink it, they won’t show.

Me too. For years I also drew digitally, but I realized that if I don’t draw traditionally, I don’t really improve. Besides, there are so many traditional materials and mixed techniques that make the whole process wonderful. In general, some time ago I stopped erasing the pencil base. I simply draw very lightly, without pressing the mechanical pencil, so that when I ink and add details and shading, the pencil is practically invisible, or it simply doesn’t show at all. I recommend using thinner leads, like 0.3 or 0.2, with a softness like 2B, so you don’t have to press hard and they leave only a barely visible trace. Using such thin leads will also train your wrist not to press too much, and it will free up your hand. That way, your wrists won’t hurt anymore. Also, as your friend said, use a kneaded eraser, the kind that looks like modeling clay. It doesn’t completely erase the pencil, but it allows you to lighten the guidelines without damaging the paper.

My preference for what it's worth: I use a softer kneaded eraser like the Faber-Castell or General's; I don't want a harder kneaded eraser or other type of eraser to shred the paper and possibly pick up ink. But for this to work I really need to keep pencil work light - I usually never use anything darker than 2H for ink under-drawing, but because that's a harder graphite I also draw with a very light hand - even apart from erasability I don't want to press into the paper to create a groove that will bias the pen stroke (I mostly use dip pens). If you're using a nice smooth inking paper, like Canson smooth bristol or Sanjoki marker pad, light pencil marks will usually come up really easily with a soft kneaded eraser. One other workflow I use sometimes is to do an uninhibited sketch in pencil (or whatever medium) without worrying about pencil pressure or darkness, and then do a tracing-paper transfer of the main lay-in to the clean inking page. This works pretty much the same but I'll use a darker pencil for the tracing paper transfer, usually HB, and try not to press too hard when going over the trace for the transfer. Erasing with a soft kneaded eraser usually works fine here too on good smooth paper. It's more work overall but it lets me do that earlier free-sketch step for expression where I don't worry about such things - inking becomes its own phase separate from the first draft creativity. ... Also, give ink time to dry before erasing! I've definitely drug my eraser over a blob of india ink that wasn't dry and left a smudge - especially if you are doing bold lines or large black areas I'd let it set a day before erasing the underdrawing.