Deleted originals from Photo library, what now?

Playing around inside the library package is a dangerous thing to do and is not recommended. You have most likely corrupted these library now.

Since you have already deleted these folders I think the best thing you can do is to create a brand new library, set it to optimise and Photos will download a new set of photos from iCloud and it will never know what you did to the last library!

To do this, follow these steps:

1. Hold down the ALT key and double click Photos icon.
2. Select Create New library
3. When it opens, select preferences (CMD-COMMA)
4. Click on 'Use as system library and on iCloud tab click Optimise Storage

A new copy of your photos will be downloaded. Since you have selected Optimise Storage only a thumbnail will be downloaded, so the total library will only be around 4GB.

Given you have deleted the originals folder and presumably do not have a Time Machine or other backup of the library package you can probably delete it once you are happy that the creation of the new library has been completed successfully.

HOWEVER, I strongly recommend you also make arrangements to create an additional library on a USB drive following the steps above, but this time instead of clicking optimise storage you select Download Originals. This will then create a full copy of all of your photos that you can maintain multiple backups of. iCloud Photos is great as a syncing service but IS NOT a backup service as no archive copies of your library are kept.