If your HTC Android device was released after 2011, then you could unlock its bootloader , HTC has built a website for HTC users who want to unlock their phones’ bootloader.
You could check out if your HTC Android device is supported unlock bootloader by visiting the HTCDev.com. The first support unlocking bootloader device is the HTC Sensation (EU) FOTA 1.45.301.2.
Unlocking the bootloader means that you now have the ability to customize software on your device. Please note that changing your bootloader can cause significant issues with your device and once you have unlocked your device, you have agreed to the disclaimer that states a change in warranty status such that in the event you render your device unusable, you are responsible for the recovery of your device, whether by repair or by other means.
You must registered on HTCDev before you start the unlock process. first, you should install the Android SDK, use it to run fastboot command and request the device idntifier token, second, you should see the identifier token is output to the PC console, record it , turn to the HTCDev website, login you account and submits device ID token via HTCdev.com portal, then waiting for the Validation, then the Key Generator will generate your Unlock key.
If your request for the unlock key fail, read this:
HTCDev.com requires a single IP authentication, and if you are behind a corporate network that may alter your IP address, certain features may not work as intended. We suggest you connect to our site via a direct connection, such as via a home network. We are sorry for any inconvenience.
After Validation, server will email the Unlock Key and commands to the you, open the Email and follow the operate manual, use Unlock Command and Unlock Key to unlock your device’s bootloader.