yum remove kernel is quite handy: I can remove every backup kernel, minus the running one. That's great when you know your kernel is working.
For the rest, I'm already using dnf/hawkey and friends. They do the same thing as yum, but ~10x faster.
Been using dnf instead of yum since installing Fedora 20, and I am pleasantly surprised by the massive speed gain. Kudos to the developers
Any way to set yumex or the new software thing in Fedora to execute dnf?
It will become the default backend for GNOME Software for Fedora 21. Fedora 22 is expected to switch over to dnf