Removing/Changing Users, Groups, and Permissions

Hi All,
So I've got a folder that I've run "sudo chmod 777 *" on hoping to force all of the permissions to be read and write by everyone, which seems to have worked, but I've got three users/groups that I can't get rid of. I've attached an image of what I'm talking about. Also, it should be noted that I'm not a regular unix user, but am pretty comfortable using the terminal with guidance. Any help on how to remove them/change them from "Custom" to Read/Write would be great. Thanks.

 

Thanks for the reply, I'll take a look at the link and give it a try. One thing just to clarify, is that I'm trying to reduce the Users/Groups back down to the three standard (Me), (unknown), and "everyone" and thereby get rid of the two (unknowns), and "everyone" that are set to custom (as seen in the attached image). Sorry if I'm misunderstanding the earlier post and it's telling me the answer to this already.

Cheers