actually.... do not remove any roots .... instead .... cut the main stalk just above that side stem near caudex
see copy of your picture
find yourself another pot ....a shallow azalea pot will work great .... whatever pot you use, will need a drainage hole in the bottom
next, layer in an assortment of rocks, about 1" or 25mm deep, in the bottom of pot.....
scatter a layer of potting medium on top of rocks ...then set your plant about a 1/2" or 13mm, higher than where it was ...then finish up with more potting medium .... wait a few days, then water in thoroughly
the rocks in the bottom of the pot will do a couple of things .....they provide drainage for the roots, (the most vulnerable part of an adenium) - restrict downward growth of those roots - and forces roots to grow outwards horizontally, instead of downwards vertically
raising the plant in the pot ...will expose more of the caudex and roots - this will give your plant that "bonsai" look