Hi and Welcome. My Name is ***** ***** I look forward to assisting you today with your question.
First of all, we're not Apple. This is JustAnswer.com, a paid support website. So if you are not satisfied with Apple, please don't rate me bad or poor.
Downgrading the OS X is not a straight forward process. When you try to reinstall, it will show the newer version message.
So you have to erase the hard drive and reinstall OS X from OS X Utilities screen by booting using Command, Option and R keys. Erasing the hard drive will delete everything from it, so do you have the backup of your files ?
If you don't want to continue, please email or contact *****@******.*** and they will cancel the question and refund the deposit you made here.
If you would like to continue, then I can send you intructions which will help you to downgrade. You only have to pay if you are 100% satisfied.