Codex- I cannot make it writeable

I am a beginner. My site is looking lovely but I need to change a few things from the original theme. ie I don’t want the calender to be shown or the ‘comments off’ quote at the bottom. I can do this on various coffee cup editors etc but just cannot make the changes on my site. I can view source info etc and know what code needs to be deleted. please help me i am pulling my hair out…. thank you.