You can access any route that you create or star on Strava.com from the record screen or your Profile page in the mobile app
To get to your routes, tap the 'Profile' button towards the bottom-right of the Strava app screen and scroll all the way down to select Routes. From here you can search through the routes that you created or starred. You can choose to Use, Star, or Share the route.
To use your route, select 'Use Route'. Once you start recording, the Strava mobile app will keep you on course. Should you need to head back early, a “Route Back to Start” feature will plot the most efficient path back to the start of your activity. If need be, you can also switch or clear the route. To get to these options, tap the Routes button (shown below).
Learn more about Strava Routes