again I have too many photos in collections...I want to delete them
You could select a photo(s) and press Delete
Are you asking how to delete photos, or how to remove photos from collections while leaving the photos in LR, or do you mean you want to remove some of your collections?
“Collection” means something specific in LR, but it’s unclear if you’re using the term the way it is used in LR.
When you say you have too many, how are you judging this? Is your hard-drive full, or are there too many photos in one folder and you don’t like scrolling through them, or are there photos you don’t want to have anymore?