Open NumJump on the device and browser profile used to save the score, open Leaderboard, and choose Delete My Leaderboard Data. Confirm the prompt. NumJump will remove the selected local player's public runs, submission-throttle record, and anonymous leaderboard identity, then clear that player's local leaderboard session.
Local Custom Game settings and personal bests remain on the device. They can be removed by clearing NumJump's app/browser storage or uninstalling the Android app.