This is a really good post about how to remove software modules that are no longer needed. I came upon this issue when upgrading from ESXi4.1 to ESXi 5.1. One of my hosts wouldn’t remove the drivers.
I uploaded the offline bundle zip to VUM and created a host extension baseline and ran it against the host. The host had a kernel panic and didn’t boot up.
I had to upgrade that particular host from the ISO and forgo update manager so all is well.
I was even given this post from VMware technical support when I called. I’d already happened upon it, but it was impressive that his blog post was on the tech’s radar.