How to close my business?

I started a vending business that never got off the ground. Made no money. I have been licensed and I got an EIN number last month. It's a sole proprietorship.

Do I need to do anything to cancel my business (ie. contact the IRS, state, etc)? If I do nothing, will I be okay?

You will need to call any federal, state, and city tax departments. You should have to fill out a form. If you don't they will keep after you about paying taxes. You might get penalized, and have to pay a minimum estimated tax. A Must Do!!!