you will have to clean up the yum transaction journals before yum (or packagekit) will be able to function properly.
With it being stuck in the middle of a transaction, if packages got updated, you will have duplicates until the old packages are cleaned up.
Your best option is to allow yum to go ahead and finish the transaction, but if you really want to toss things out and leave a transaction only half finished, there is a way to clear the transaction journals, but you will probably end up with duplicate packages as a result.
To have it clean up the transaction journals without actually completeing the transaction:
I would recommend to cleanup duplicate packages after going this route, though..
I do have to say that you are risking leaving your system in an unknown and possibly unstable state by just clearing the transaction journal, though. For example, if a package got updated, but a dependency did not get update, then that package may not even work.
You say that you got a kernel panic from doing the same exact
update? If you know what caused the kernel panic, you could exclude just the problem package and still allow yum-complete-transaction to run and update the rest of your system.
yum-complete-transaction --exclude=package name