Clearing Failed Backups

Backups to Dropbox, run as Scheduled Tasks, haven't been working for me for a long time. Probably an environment issue relating to cron, but not really worth billable time to wrangle with the hosting provider, as the client never logs into Perch (sad!), and I run a backup manually whenever they ask me to make a change on the site.

Unfortunately, after messing with this issue for a while, I now have huge lists of failed backups built up in the Scheduled tasks page and the Backup details page.

Question: can I delete these failed backup entries directly in the db without messing things up? What table are they in?

Feature request: "Delete" buttons on the Backup and Scheduled task log entries. Or a little "Clear List" button in the corner?