If you forgot your Windows 8 local user password or PIN on Surface Pro/RT, a way is to log into another admin account or use Previously-created password reset disk to change the password. If these suggestions is not working and the tablet does not recognize password, try the following tips to do a full reset and recovery it. Note: It will delete all your files.
How to reset forgotted password on Surface Pro
* First shut down the device and then press Power button to turn on.
* When Surface Logo with circling dots display on the screen, hold the Power button for 10 seconds and repeat it since you see the words “Preparing Automatic Repair”.
* In Recovery Mode, tap “Skip this drive” with Bitlocker, and go to Advanced Options > Troubleshoot > Reset > Just remove my files. You need to wait for about 20 minutes.