<human>: Hi all,

So here's a short background, I am going to be a senior this semester and last spring I joined a brand new on-campus organization. It was pitched as a co-ed social/service organization made up of around fifty "committee" members (which I was selected for) and around another forty or so "general members" on top of mentors and directors. Anyway, it seems like those who created the organization and decided what students were accepted chose mostly previous friends of theirs with me being an exception. This makes things difficult because it seems like everyone except me is already close with one another. On top of that, it seems like most of these people are pretty serious partiers which really conflicts with me because I don't party at all and I'm more of an introverted type (why did I join this organization, right? I'm not sure). Well now the semester is about to start and I really don't want to be a member of this organization. It's my last year in college and I really want to enjoy the whole thing (minus the classes of course). I was wondering if you all have any tips or suggestions for how to go about this? I'm thinking that I will email the director and tell him. I just don't know what exactly is the best thing to tell him or how to phrase it. I'm thinking I could use the excuse that I really want to focus on classes, which is true because I am an engineering major and it sounds like senior year can be killer. Please, let me know what you all think. Thanks!

Can you summarize the given text in a few sentences?
<bot>: I joined an on-campus organization last semester that isn't what I hoped it would be and now I want to resign. I am wondering how to best tell the director that I am resigning?