[HTC One Max] neodiver:
Root Your HTC One Max

If your One Max is on Sprint then you can easily unlock bootloader through HTCDev. Then you can Install TWRP 2.6 and use it to flash superSU 1.91 (Google). You will then be rooted and ready to rock and roll. You can follow this Youtube video: http://www.youtube.com/watch?v=qpj6dEMn9dw for procedure if you're unfamiliar. The vid tutorial is for the HTC One but is the same procedure for One Max. You will need to download adb and fastboot (and appropriate drivers if you are using a windows machine). No drivers are needed if you are using a mac or linux box. You can get the necessary files from here: http://developer.android.com/sdk/index.html. Download the appropriate ADT bundle for your platform.

Windows drivers SHOULD be installed by default the 1st time you plug in your phone. They are however installed along with HTC Sync which can cause you connection problems. I would recommend NOT installing HTC Sync as you would most likely have to uninstall it later in order to get these procedures to work. Instead try this link for HTC Drivers: http://xdaforums.com/showthread.php?t=2089508. Make sure drivers are properly installed BEFORE you plug in your phone. Windows can be a PITA so be sure you can disable antivirus, firewall, and any other running processes that may impede your ability to achieve and maintain a solid connection to your device.

You will also need to enable USB Debugging on your One Max. To enable USB Debugging you need to go to Settings > About > Software Information > More > Build number - tap Build number 7 times to enable developer mode. After you get the window saying "developer mode has been enabled" go back to the main menu in Settings and you'll see you now have "Developer Options" added. In there you will have the ability to enable USB Debugging

Create a folder for ALL your development files that you can easily CD your command prompt to. (Ex. "C:/onemax" for windows or "desktop/onemax" mac/linux) Follow video.

If you are using a Verizon One Max, you will be unable to unlock your bootloader through HTCDev. In this case you will need to S-Off your device you can follow this guide if your Hboot is 2.46 or lower: http://xdaforums.com/showthread.php?t=2473644. If your Hboot is 2.47, rumrunner will not work for you. You will need to consult the firewater guide instead: http://xdaforums.com/showthread.php?t=2632385. Once you are S-OFF, you can pretty much do anything you want on your One Max. FYI Hboot is HTC's bootloader. You can find out your version by 1. going into Settings > Power - then untick Fast Boot option. 2. shutting down your phone, then 3. hold the volume - key down firmly, then hold down power button until your device boots into the bootloader. Hboot version will be shown at the top of your screen.

Spend a little time familiarizing yourself with whichever procedure you require.

Quadruple

check you are using the CORRECT FILES for your One Max. You will need a properly working development environment regardless of which procedure you will follow, so set it up first!

Here's hoping you have a

Sprint

One Max and a

Mac

LOL Seeings how you only need a simple root! ;)

Good luck!