The first expression is right. "走“ emphasize the way to get to you destination, such as "走(walk)去(to)书店" and"跑(run)去(to)书店". while "去" is just like prep "to", it stress your direction or destination. Hope it is helpful

”我去书店要怎么走“ is the correct expression. In this one, 去 represents the act of going and 走 represents the way to get there. Literally, it reads "我（I）去（go to）书店（book store）要（should）怎么（how）走（to get there）？“ The second expression makes no sense; you need to add more to it in order for it to be correct, as rowdymrlotso already showed you. Basically in the examples you've provided, 去 just means "to go," but 走 is the method of getting to your destination (it covers both directions and means of transportation).

I am assuming the two statements were meant to be a question. 我去书店要怎么走? It literally translates to "I go to the book store, how do I walk." It essentially means "I am going to the book store, which way do I walk?/how do I get there?" 我走书店要怎么去? This sentence can be made even more clear to the listener by phrasing it this way: 我要走去书店，应该怎么去？Which means, I want to walk to the book store, how should I get there? 去 means "to go" 走 means "walk" and "to go" as well, in your sentence it means "to go to a place by walking there."

去 = go, does not specify the mode how you do it. 走 = walk or run (classical Chinese, 走馬 (running horse) 走狗 (running dog i.e. traitor, someone's lackey etc, 走火[入魔] (running fire, a technical term used in physciology/tcm), 走水 (running water, a euphemistic way of saying there's a fire broke out in the palace, to avoid the tabu word of fire)