Yes, you can easily reduce the price.
1) Go to your Kindle Bookshelf.
2) Click on the book title you want to reduce.
3) Scroll to the bottom of the page (you don’t have to reload your book or graphics)
4) Click “Save and Continue” and you will be taken to the “Rights and Pricing” page.
5) Input your new price. Keep in mind, if you were priced from $2.99 to $9.99 at a 70% royalty and you want to reprice to $.99 to $2.98 you will have to choose the 35% royalty option.
6) Scroll to the bottom, tick “By clicking Save and Publish below, I confirm that I have all rights necessary…blah, blah, blah”
7) Click “Save and Publish” and you are all set.