There are two ways of changing your SharePoint list or library URL. The first one is, of course, using PowerShell which I am not going to discuss now. The second one is using SharePoint Designer. You need to have site collection admin access to do this.
Suppose you want to change the URL, http://sitename/sites/testsite/Lists/Bad List Name/ to http://sitename/sites/testsite/Lists/GoodListName/ using SharePoint Designer then follow these steps:
1. Open your site using SharePoint Designer
2. Click All Files from left navigation menu
3. Click Lists from the list of All Files
4. Right click into Lists ->Rename and change it from Bad List Name to GoodListName.
5. This will change the URL of your list
That is it…