If you really would have a problem, it wouldn't be so hard to google 2 seconds to find out how to open terminal in recovery.
So if it isn't even worth your time to open google then I wouldn't post in this forum, because you're then just wasting other peoples time.
In the menubar right when you boot to recovery, there is a tab called utilities
Just to keep you all posted, I have unmarked the old post (which was marked as solution) and marked the correct solution now.
There is a bash script to uninstall XFence:
Seems to delete everything - I had already followed the instructions above to delete most files before I found the script in /Library/XFENCE
Uninstall should not be the only option. The bug, which I was told is a design feature, is that "disable"is not persistent; that is, when you reboot it automatically reeables itself. So, if you want to set up a new Mac using Disk Target Mode you are prevented from doing the transfer because XFence has reeabled itself. Or, as others suggested, you find that the product doesn't function well enough, you should beable to persistently disable the product. This design feature is a DESIGN BUG!
I have found a tested and working solution for those, who cannot remove XFENCE.kext from /Library/StagedExtensions/Library/Extensions/ - even via Single User mode:
Delete the actual kext from /Library/Extensions/ first, then run "KextWizard" (downloadable at https://mac.softpedia.com/get/Utilities/Kext-Wizard.shtml) and enable both checkmarks under "System/Library/Extension, i.e. "Repair permission" and Rebuild cache" - then click "Execute".
This removes the stubborn XFENCE.kext from the cache (that /Library/StagedExtensions/Library/Extensions/ actually is) and keeps it from being activated over and over again.