I am practicing engineering drafting and sometimes I am near on finishing my work but suddenly I make a mistake. Is it possible to remove the ink? If yes, how? Where can I buy such tools? I am using a Staedtler's Mars Matic 0.5mm.
To remove such ink it needs to scraped off, usually with a scalpel blade. This works well on thicker and more studier media such as film or vellum, but it will always be obvious where the erasure was made.
Depending on the amount of ink that needs to be removed and the robustness of the media, sometimes an ink erasure can work (such as a Staedtler blue ink eraser, Mars Plastic Combo), but again it will be obvious where the erasure was made. This can work on paper, but only with thicker robust paper.
If you need to present a drawing of professional standard, redraw the entire drawing.
Is it possible to remove the ink?
A quick Google search isn't turning up anything, as I more or less expected. Ink isn't meant to be erased, so I'm going to hazard that there is no product that will erase the ink for this pen.
Normally, the only "erasable" ink pens I see are the cheap, consumer-grade pens that use a more standard-grade ink (erasable is a relative term - I've never seen an erasable pen where you can totally remove the ink from the paper). Since the Staedtler pens are more professional-grade and use higher-quality inks, they are made to be indelible.
sometimes I am near on finishing my work but suddenly I make a mistake.
The tongue-in-cheek response to this would be "stop making mistakes." I know that's not really possible given that we're all human. However, when it comes time to inking, you should really be focused on tracing lines that you already know are correct. Inking is not the time to make changes.
Yes, it can be removed but it is a delicate task requiring some experience...I first did this over 50 years ago. You should be drawing on some heavy velum that can withstand the erasing. You will need an erasing shield and electric eraser with the coarse dark grey eraser to gently sand a layer of paper off with the ink. It's easy to erase a hole. If you're going to do a lot of ink drafting you may want to look into mylar! Goid luck drafting ....computers suck!