Destroying a black hole with rockets, shooting lasers at it, smashing planets into it, is not gonna work. Nothing like that would work, more interestingly whatever you throw at it will just make it bigger and angrier. So the only way to destroy a black hole is to sit back and wait for it to evaporate. That's not actually useful if you're getting pulled into a giant black hole. But what about the idea of adding antimatter to a Black Hole, isn't antimatter the total opposite of ordinary matter. Let me put it like this, if you add a positive number and a negative number together, they just cancel each other out, right? But it is not possible either, did you say, why? Well let me explain, Antimatter is precisely the same as ordinary matter, except everything with antimatter is backwards. Spin directions, electrical charges, and configuration of all the sub-particles that make it up.
Obviously, the gravity of a black hole is so powerful that nothing, not even light can escape it. So all energy would just be turned immediately into more black hole. So, if these two objects came together, you will eventually end up with a black hole with double the mass that you had before.
Also, forming an antimatter black hole is impossible with current technology. Antimatter is created in particle accelerators, protons are speeded in a huge ring, pushed to approximately the speed of light, and then smashed into each other to form antimatter.
According to NASA, would it will cost nearly $62.5 trillion to create one gram of antihydrogen, the most costly material we could probably make on Earth.
It's possible that the Large Hadron Collider can create microscopic black holes, even though none have been produced yet. So the bottom line is: If a regular black hole and an antimatter black hole got smashed into each other in space, they wouldn't disappear. So Antimatter is not the option. It will only make the black hole more gigantic.