How to remove soil smell from beetroots?
Beetroots do have an earthy smell, that's normal and can get stronger if you just cook them in water. I can think of two approaches to work with this:


Try roasting them in an oven (optional: wrapped in some aluminum foil) until tender. They will develop a sweetness whith perhaps some earthy undertones. 
Add an acidic component like vinager or lemon juice to the cooked beets and let rest for a few hours (or pickle them).


But you might consider how/where the beets were grown: If the "soil" smell is too strong, it might be because there was too much fertilizer or manure in the soil, which beets tend to absorb.