How can I erase old pictures from iCloud, which are not on my phone anymore, without turning on iCloud on my phone?

I just discovered connecting on my Mac to iCloud that I have stored some old pictures which long time erased from my life. I want to erase them, with my phone not connected to iCloud. I don't want those pictures to flood again in my phone. its from a painful past. When I try to erase them from iCloud, the trash icon is not active, therefor I cannot delete them. What is the problem? I have already lost more than half a day searching information and reading other answers from the community but none of them reflect my situation. thanks!