how to delete the photos in Event ?

Are you using iPhoto for Mac?

The "Events" view and the "Photos" view are showing you the same photos , but differently. They are no duplicates, but only different ways to access the same photos.

If you delete a photo from the "Events", it will be deleted from your iPhoto Library completely and the photo will be lost. The events are showing the photos grouped by the import session, and "Photos" is showing you the same photos as an endless stream.

If you need to free storage, consider to move the iPhoto Library to an external drive, to have more storage for your photos.

You probably are on a path to failure - you must have a minimum of 10GB of free space just to operate and should have 20GB - 10% of your disk is better - chances are that you simply can not remove enough photos to free enough space - you probably will have to either get a bigger hard drive or an additional external hard drive formatted Mac OS extended (journaled) and run your Photo library there

And of course Photos and events are not separate photos - simply two different ways of viewing the same photos - you can not delete form one and not the other as neither exists as a place - it is just a view of the library and if you delete a photo form the library it is gone everywhere

If you are using iPhoto where you posted the answer to your question is to select photos in events and press delete then empty the iPhoto trash and the system trash although that is very likely to be no solution or at best a very short term solution -- how much free space do you currently have?

LN

Deleting Photos from an iPhoto Library

1 - from an Event or the Photos mode: select the photo(s) and use the Delete key to move the photos to the trash bin. Then empty the iPhoto Trash bin as follows:

2 - from an album, smart album, book, slideshow, card, or anywhere in the library use the key combination of Option+Command+Delete to move the selected photos to the iPhoto Trash bin. Empty the iPhoto Trash bin as above or with the key combination of Shift+Command+Delete. You will see get this message to either continue or not.

3 - once the iPhoto Trash bin has been emptied the files are transferred to the Trash Bin in the Dock. When you empty the Dock's Trash bin the image files are permanently removed from the hard drive.

NOTE: deleting a photo from an album, slideshow, book, etc., with only the Delete key only deletes that photo from that item. Deleting a photo from an Event deletes ALL occurences of that photo in the library.