How do I remove photos on my phone? I backed them up on my computer. Is there a way to view the photos that I want to delete?

How do I remove photos on my phone? I backed them up on my computer.

my current photo settings

i cloud photo library -turned off

my photo stream --turned off

i cloud sharing--on

summarize photos --on

I have these settings so that i manually sync phone directly.

I lost photos a while ago and I was advised to do this.

I just don't want to accidentally lose photos so I am asking. thank u.