Other than waterjets (which use garnet or diamond abrasive) or plasma, the usual way of removing hardened tool steel is grinding with carborundum (silicon carbide) or even aluminum oxide grinding wheels or cutting discs. From there you just need to figure out what you have (dremel, angle grinder, chop saw, etc.) or want to pay for, and go from there.
If I were a betting man I would put money on picking up a basic dremel or corded angle grinder at most any pawn shop most any day of the week for $20-40. And you can get a basic Ryobi angle grinder (plenty good for occasional non-professional use) for $40 brand new, or a Harbor Freight Dremel-style tool for $10-15.
But before spending a dime make sure you understand Bob's excellent explanation above.