Find the Bindings Folder:
%localappdata%Frontier DevelopmentsElite DangerousOptionsBindings
You want to find the 2 binding files we need to deal with. For me it was "Custom.3.0.binds" and "Custom.4.0.binds" which correspond with the Horizon and Odyssey binding files. For you it might be different but you can go off of the modified date of the .binds files.
Backup Custom.4.0.binds (or both to be safe)
Open both files side by side
In Custom.3.0.binds, delete the first 2 lines, and the last line in the file
<?xml version="1.0" encoding="UTF-8" ?> <Root PresetName="Custom" MajorVersion="3" MinorVersion="0">
So you are left with just the Horizons key entries
In the Custom.4.0.binds file search for:
This is the first entry in the controls for the new stuff. Delete everything between this line up to the 2 header lines quoted above. Make sure to leave those 2 lines at the start of the file.
CTRL+A to copy the contents of the Custom.3.0.binds file and paste it where you deleted the other lines in the 4.0 file, making sure to check spacing and tabs. Save the 4.0 file and close the 3.0 WITHOUT saving.
I would restart the game to be safe but I was able to do this at the main menu.