Yes. If you delete a photo from your computer, it will delete from Dropbox Carousel. Because Dropbox Carousel is just a viewer of the photos which you have in your Dropbox account. So, if you delete them from Dropbox, they will be deleted from Carousel too. Dropbox Carousel is a photo and video management app offered by Dropbox. Here photos are organizes by date, time and event and backed up on Dropbox. If you add something in Dropbox folder on computer, it will automatically backed up to your Dropbox account. So, if you delete your photos from Dropbox folder on computer, it will be deleted from Dropbox Carousel.