Letting users remove webform submissions they've made earlier I have a website where people can sign up for events. The client now wants the users be able to delete their submission for the event, by entering their email address, displaying a list of events they're attending, and choose which event they want to remove themselves from.

Is there any module that adds this functionality, or is it something that can be done out of the box?
Implement sign ups as nodes instead of as webform submissions. Then you can grant the delete own [node type] nodes permission to allow users to cancel the sign up.