Horde commanders can be swapped. It’s my preferred method of doing things with Chaos.
You have to go into the skill details for the current lord, the same screen you go play with when a lord levels up. In there, hidden to the bottom right, will be a little boot button. Click that to boot them out of the horde and turn over control to another lord. The fired lord will do the standard spend-5-turns-sulking before they can be recruited again of course.
The advantage to doing things this way with a horde faction is that the old experienced lord should already have the blue line skills to boost horde growth. So giving a fresh horde to an experienced lord will shorten the amount of time that it’s useless and building-less while waiting for the population to grow.