To bulk delete scheduled or recurring posts:
Click Toggle Select located near the top-right of the Scheduled page or the Recurring Posts Lists Items page.
Next, select the posts you want to delete by clicking on them, or click Select All located near the top-left of the page.
Once you have selected the posts you want to delete, click Delete Items located near the top-left of the page.
If you are sure you want to delete the posts you have selected, click Yes, Delete in the window that pops up.