I’ve done some tests while integrating the new Google Play Games with fake scores, now I need to reset the leaderboards before publishing my game!
I found this REST API:
But this seems to be related only to web games, not Android games:
“Use the Google Play game services REST API to set and retrieve game services data from your web game”
I ended up switching all my leaderboards in the Developer Console to use “lowest scores are best” instead of the previous “highest scores are best” and this seems to have reset the old scores that were saved. It’s a bit of a hack but very useful. You could probably switch back again and everything would still be cleared.
Updating the answer as it is now possible to reset the leaderboard during development.
You can only reset player progress data for your draft leaderboards.
To reset leaderboards in the Google Play Developer Console, click the
button labeled Reset leaderboard progress at the bottom of the form
for that event. To reset leaderboard data programmatically, call the
Management API Scores methods.
Reset Test Achievements and Leaderboard Scores
As of Sep 9 2013 (From the Public issue tracker for the Play Games platform):
If you are still in test phase, you can reset your Achievements by deleting your account from the Test list in your developer console and adding it again.