Once into the Dell Venue 8 or11's UEFI BIOS, disable Secure boot ... password you got lost and would like to perform password reset on. Click on the Reset Password. -> Restart the tablet and return to the sign-in screen where you won't have to type in a password.
Hardware Key Reset
If your device is not working because it is frozen then you wouldn't be able to reset it with the software. So the next option would be the hardware method.
1. Press and hold down the Power button + Volume down button + Camera button all at the same time until the device vibrates, now let go of the Power buttonwhile continuing to hold down the Volume down button and theCamera button.
2. Shortly you should see the message displaying "Are you sure you want to format?", you can now release the Volume down button + Camera button.
3. In the format screen you have the option to either Format or Cancel. Tap on Windows key Format if you are confident to go ahead.
4. Press on the Windows key again to confirm your choice.
Your device should now begin to format the device and shortly should startup with the Start-up Wizard. Ensure you device have the battery power while doing this
You can click the link below to choose your tablet from the list. Once you choose your device you can download the online manual. The manual provides information on performing task within your tablet.
Dell Support http://dell.to/1C6plZK
Dell Social Media and Communities
Your best bet is to google your specific device, but some have a small hole on the side and you can use a paper clip. Or power off, then power back on holding the power and volume down button down until a menu shows up on screen. You may have two or three options such as hard, soft, or recover reset.