Another question that is repeated the most on the web is that of How do I reinstall OS X Mavericks after upgrading to OS X Yosemite?
This is a question that has several answers and several methods to carry it out. The simplest and safest thing in the case that you want to return to OS X Mavericks from your Mac, is to have the original OS X Mavericks installer on a pendrive or SD and in this way carry out a clean installation OS X on our machine.
If we do not have the installer we can access a Mac that is in the version of OS X Mavericks or search for it on the net and download it to a Pendrive / SD, but the latter we have to be careful because it is possible that there is a failure or is incomplete. It is best to directly search for a friend's Mac with Mavericks or ask someone who has the original on a Pendrive for the installer. If we don't have the option of getting any of this, keep reading and discover the method by WiFi download.
Before starting with this tutorial that allows the download via WiFi of the native OS X of our Mac I recommend the installation with USB again because it is the safest and most reliable. If you still want to try this option to install OS X Mavericks on your Mac, here we leave it, but before you get to work I advise you to read the entire tutorial before and in this way understand the steps.
First step as usual: backup
This is a very important step to avoid losing anything important and therefore we always recommend make a backup in Time Machine or wherever we want. If you have a dedicated hard drive exclusively for your backups, better, as this ensures that you will not delete it in any case even if we have to format the Mac's hard drive.
We don't have to lose data if we do this process of downloading the OS X via WiFi, but it is advisable to always have a backup copy when we mess with these things in case the flies.
We started the process of downloading OS X Mavericks
Another important fact to keep in mind is that if our Mac had OS X Mountain Lion as standard, the recovery will install OS X Mountain Lion on the machine, entering a loop since you will not be able to install OS X Mavericks because the current version is Yosemite, so if your Mac you bought it without source OS X Mavericks You have to resort to the Pendrive method to carry out the installation of OS X. If your Mac had Mavericks from origin you can continue.
Now once we have our data safely and we are clear that OS X Mvericks will be installed, what we have to do is restart the computer and before the typical startup sound sounds, we hold down the keys Alt + Command + R. In this way what we are going to achieve is that our Mac enters Recovery mode directly and we will see the typical circle that the Mac shows when something is being downloaded, below the text explains that the system is recovering from the network. Now it will depend on our connection how fast the download of OS X Mavericks takes place.
Once the download of OS X is completed via WiFi, the Mac offers us the possibility of carrying out a clean installation or updating on top of OS X Yosemite. If we don't want to update clean We just have to click on install and this OS X Mavericks will be installed directly on top of the current one, keeping all the settings we have on our Mac.
If we want to update by making a zero installation removing old configuration and avoiding possible errors (this is the option that we recommend) we have to enter the option Disk utility and erase. Once the content of the hard drive where we have Yosemite installed has been erased, we go back and click on Reinstall y Continue.
Ready! Now touch wait for the process to finish and then enjoy OS X Mavericks on your Mac.
For those users who They didn't have OS X Mavericks when they bought the Mac this method does not work for them and therefore you need to have the installer on a pendrive to carry out your downgrade. We leave the link of how install from scratch OS X Mavericks with a USB.