Log into your profile and follow these steps:
1. Select the menu icon on the top right of the page (to the right of your picture), and under the menu that appears choose Settings, then Account Settings:
2. Under Account Settings, select 'change' next to Location to update this information. Type in the new location and choose from the drop down list. Enter your password or follow the prompts in the Facebook pop up. Select Update Location when you're done.