Hi Dennis,
Thanks so much for reaching out!
Unfortunately, by itself our plugin cannot bulk change events to all day events. However, I’d recommend taking a look at the solution provided in the following forum post, with the addition of a third-party plugin, and see if you are able to modify it in order to achieve the results that you are looking for:
https://theeventscalendar.com/support/forums/topic/bulk-edit-event-month/
You can also add this idea to our Feature Requests, as we tend to implement ideas based on customer feedback, so your input is greatly appreciated:
https://tribe.uservoice.com/forums/195723-feature-ideas
Let me know how it goes!
Thanks,
Jaime