Sorry about that, the questions were asked so close together, that I thought it must have been you.
At any rate, there are no ‘originals’ to delete, as EWWW replaces the originals with the optimized versions.
Unless you mean that you want to keep only the resizes that WordPress generates, and remove the original image that you upload after things are processed.
If the latter is the case, there is no way to do that without WordPress breaking (that I know of). BUT, you could use the resizing settings on EWWW’s advanced tab to minimize the storage space required to store your original images. Resizing of the original is performed after all the other resizes/thumbnails are created, so you could probably set it to something like 50×50 and then they wouldn’t be using much space, although it might be better to play it safe and go with something like 1200×1200, so you at least have a somewhat usable original image should you ever need it for anything in the future.