Trying to withdraw some of my contributions from my Vanguard Roth IRA

I have a Roth IRA with Vanguard. I chose a Roth IRA so that I could withdraw my contributions at any time. I looked on the Vanguard site for 20 minutes trying to find out how to do this. Finally, I clicked on the chat button for assistance. Here is the response I got:

Due to the complex nature of your question, it would be best for you to speak to one of our associates by phone. You can reach us at 800-805-0614.

Not helpful at all.