1) Post type: You can delete Post Meta by choosing post type post/page..
2) Post: You can select posts whose post meta field you want to delete.
3) Meta fields: You can delete a post by only meta key.if you want to delete post meta key and its value so also you can do it easily using this plugin.
4) Date Interval: You can delete a post meta using the 3 option in the delete post meta date interval.
=> Older than: You can delete post meta that are older than your selected days
=> Created within last: You can delete post meta that are created within last your selected days
=> Created between : If you want to delete a post meta between the start date and the end date. Then this option will be helpful for you
5) Detele Time: WP Bulk delete Pro provides functionality to scheduled delete at a particular time. and You can choose the scheduled at option at Delete Time to scheduled delete. it has 2 options.
Delete now => It will start delete operation just after you press the delete button.
Schedule Delete => If you want to run delete operation later at particular time. You can also repeat delete operation Once Hourly, Once Month, Once-Weekly, Twice Daily, Once Daily. You can see repitative scheduled deletes at WP Bulk Delete>Schedule Delete page