No, you can not. There are two reasons why it is impossible to kill these monsters with a cannon.  First of all, as we have discussed, they have an immunity to a lot of attack types. You can only hit them with leaf-bladed weapons like the axe, spear, and sword or with broad arrows and broad bolts if you are ranging them. The magic dart spell is also effective to them. Everything else is going to fail, including your cannonballs. They will all hit zero, so do not waste them. Second, you can not use a cannon in the Fremennik Slayer dungeon. You cannot put a cannon here because the air in the cave is too humid. The fact is that the Turoth at this moment can only be found in the slayer cave in Fremennik. So, unless they ever spawn somewhere else you won't even be able to hit them with a (futile) cannonball.