Can this plugin optimise previously uploaded photos

Hi there I read from the post below, it said that this plugin can optimise previously uploaded photos.

My questions are:

1) I m not sure how to get that done can someone please help? Thanks.
2) Once it optimised the previously uploaded images, will it delete the big original image files? (I need that to happen to reduce my disk storage space).

Thanks in advance.

https://www.wpbeginner.com/plugins/best-wordpress-image-compression-plugins-compared/