This works in both Windows 8.1 and Windows 10
You can use the registry editor do disable the lock screen image, which will remove the need to swipe the lock screen every time you want to unlock your computer (so when you press WinKey + L, it only shows your logon image and password field):
In the registry editor, navigate to the following key (if the key does not exist, you will have to create it manually):
Select Personalization key and in right-side pane, create a new DWORD NoLockScreen and set its value to 1.
Close Registry Editor and log off or restart Windows to take effect. It'll completely turn off lock screen.
If you want to restore lock screen in future, just delete the DWORD or set its value to 0.