You have couple of options how to set your download location for the Oculus Rift. Follow this guide how to successfully finish the different ways for this typical question.
Install Oculus Rift runtime in different directory.
Step 1. With the new release of Oculus runtime you can change the install directory of the Oculus. With this move the download directory will also change. Note: you must first uninstall your Oculus Rift.
Move Oculus rift to another folder and link the folders with symbolic link
Step 1. Close Oculus Rift
Step 2. Move the Oculus folder to your wanted location
Step 3. You will also need to create a symbolic link that will lead you from your old folder to your new chosen location.
■ Open command prompt
■ Enter this command: mklink /J "C:\Program Files (x86)\Oculus\Software" "<your_wanted_directory>"