So if I'm comprehending your question correctly you want to be able to downgrade back to Mavericks.
You will have to download or torrent it externally without Apple's permission but seeing as it was a free upgrade when it was available there should be no problem.
That being said here's a (broken) link to a download of a bootable DMG file.
Also you will need a USB Flash Drive of 8GB or higher.
And if you want to you can use Time Machine to backup your Macs files and preferences to an external drive.
Here's a link to a helpful video on that: https://www.youtube.com/watch?v=xgYqcL7_0BI
Now onto the good stuff:
Once the torrent is downloaded open Disk Utility.
Select your flash drive from the list.
Click the 'Erase' tab.
Click the dropdown next to Format and select 'Mac OS Extended (Journaled)'.
Then in the name box you can put whatever name you want.
Then click Erase and confirm it as well.
BEWARE AS IT SOUNDS IT DOES ERASE ALL OF YOUR DATA FROM THE FLASH DRIVE!
Once it's finished select the partition that has the name your entered and click the 'Restore' tab.
Locate the file you downloaded earlier and drag it into the 'Source' box.
and then drag the partition you made into the 'Destination' box.
Click the 'Restore' button in the bottom right.
Then let the magic happen. :)
Once its finished shut down the Mac and turn it on again while holding the 'option' key until the grey screen WITH the drives to select pops up.
Select the drive you made and it should boot into a recovery-like drive.
From there you should be able to format the drive with Disk Utility and reinstall Mavericks.