Q.should the whole root be covered or should part of it be above ground
I have a sago palm and I got it from Walmart. When I repotted it, I planted it with only half of bottom in soil. Should it be covered and planted like they had it.
You should plant it the way it was at the store. Contrary to what many people think, growers practice good horticulture, because it is in their interest to have plants that are healthy and grow quickly. It is for this same reason that plants fresh from the store need neither repotting nor fertilizer. This article will give you some more tips on sago palms: https://www.gardeningknowhow.com/ornamental/trees/sago-palm/how-to-care-for-sago-palms.htm