Staples and RadioShack have removed Amazon lockers from their stores about a year after starting the program as competition stiffens with the online retailer. The chains began testing a system last year in which Amazon shoppers could have a Web order delivered to a store and then pick it up for no extra cost. This allowed customers, especially urban apartment dwellers, to avoid being home to receive a package or risking a delivery being stolen because it had to be dropped off on a doorstep or in a lobby. The decision to enter a partnership that made life easier for Amazon’s customers came at a time when the online retailing giant was already a major competitor to both chains. “That was a little bit odd, but what they were hoping for was that when customers would come in to pick up stuff from the locker, they would pick up additional items,” said Brian Yarbrough, a retail analyst with Edward Jones & Co. in St. Louis.