From your Shopify admin, click on Apps, and then look for the Store Locator app.
Click on the downward facing arrow, and select "Edit Proxy URL".
Choose from any of the available options in the dropdown, and replace "store-locator" with any other text. Click Save Changes when done.
To add the link to your store navigation, Shopify has an article available here: Add a link to the main menu navigation
If you select Web address from the dropdown menu a new editable text field will appear instead of the additional dropdown. In this field you can enter the URL of the web page you want to link to.
In a nutshell, if your store address is www.myawesomestore.com and from the steps above, your proxy URL was entered as /tools/stores, the full address should be entered as http://www.myawesomestore.com/tools/stores.