Deleting online scores

http://musescore.com/help → http://musescore.com/help/sheetmusic-sets#37583

Instead of uploading a new score, you can always replace your current one by following the 'edit this score' link on the score page. Next you can upload a revised mscz file. This way you retain all your score statistics and comments.

For MuseScore 2.0, when you upload a revised score, it will ask you whether you want to replace the original one or upload it as a new score.