Question about quitting earlier than on contract

I have not started yet, I process in on the 9th. But it is possible that I might have a major conflict later on this summer that would intersect with the time I said I could work on my contract. Would I be able to quit at an earlier date without there being negative ramifications? This is going to be my first job, and I am going to be a park sweep. The possible conflict is an internship that could be very good for my desired career.
I do not want a blemish on my work resume, especially since this will be my first job, but my career resume is of more importance to me. How would I go about changing my contract end date if I have to?
Thanks, I really appreciate it.

The best thing you can do is be up front with them about it. You might be able to get your dates changed, or at the very least be able to quit early without being put on the no-rehire list. But there's certainly no guarantees. Talk to your manager and see what can be done.

thanks =)

Yes the first step is talking with the people who can help you, Reginald.

And while I am answering you Regi, why did you copy another person's signature? That is kind of weird.

Talk with your manager ASAP! Don't wait because if you tell them now and fix your contract now, they can find a replacement. If you wait and they can't find a replacement, you're still obligated to your schedule which means points, write ups, and either no-hire or conditional rehire status.