To update / change submissions submitted to the current open contest:
Upload it again using the same name and filename.


To remove submissions submitted to the current open contest:
Send email to manager@composition-contest.com asking to remove it.


To remove submissions AFTER a contest is run:
You can't.
When you accept to participate in the contest, you agree to the rules.
It is non sense to ask to be removed form a contest AFTER the result.


Thanks for your participation!