Hi all, I'm new to this forum

I just purchased a second hand EF 400mm f/2.8 MK II (the old non-IS version)

The previous owner, however, decided it would be a good idea to mount the tripod foot in reverse (I have no idea why)

I can't for the life of me work out how to put it back as it should be!

Please does anyone know how to fix this? It is quite annoying and means balancing the lens is difficult!