How can I remove a MultiRom ROM? I have a secondary ROM I'd like to remove, but trying to remove it using the TWRP Multirom menu or the Multirom app in the primary ROM fails (shows failure and force quits respectively). Is there any other way to remove the ROM?

One possibility is to completely remove multirom and all associated  secondary ROMs but that's really overkill and I'd like to avoid that as far as possible.
I'm not entirely sure why this worked but what I did was to:


Wipe data from the secondary ROM I wanted to remove
Reinject the current boot sector


Then I rebooted and was able to successfully remove the ROM via TWRP.