To disable Xposed completely from recovery,
- Boot into custom recovery
- Go to File Manager (usually under Advanced)
- Navigate to /data/data/de.robv.android.xposed.installer/conf/modules.list
- Delete modules.list
- Reboot System
The deleted file simply controls which Xposed modules are loaded on startup. Deleting the file disables all Xposed modules.
After you reboot, all of your Xposed tweaks will be disabled. To re-enable Xposed modules, simply start up the Xposed Installer app. Then go to modules and make any change. This will re-create the modules.list file that you deleted in recovery.
There might be quite a lot of people who already know but this is for the benefit of those who don't know and end up wiping data and flashing everything from scratch.