csosa on "prevent link backs"

I don't mind if sites link to the website, in fact there are several I plan on leaving.
I am new to SEO and I have read that bad links or a bunch of links that are spam hurt with search engines. The website I am referring to is my church website that I am managing. There are several dead page's linked to the website. One of the link backs is a porn picture. I'm not hating on porn but If possible I would like to be able to screen who has a link back to my site.
I am trying to figure out how to get certain links removed.
Do you have any tips???