There are a few different ways to remove items. The easiest method is to use Photoshop's content aware fill. Use the lasso or pen tool to select the object that you want to remove and then go to Edit > Fill and select 'content aware fill' and click 'ok'. Photoshop will remove the object and replace the pixels automatically. This works well in a lot of situations, but it's not perfect. If the background is really busy, Photoshop will not be able to get a natural look with this technique. The clone stamp tool is a good option when you need more precision.