question about icloud unlocking without password.

If necessary, if you are the original owner, contact Apple. They can remove the Activation Lock if provided the required paperwork. Either take the device, the original purchase receipt with the serial number, and a photo ID to the nearest Apple Store (if it has reopened)

Genius Bar Reservation and Apple Support Options - Apple.    

or contact Apple ID Support. 

 Apple ID - Official Apple Support.    

Contact Apple for help with Apple ID account security - Apple Support.  (Link doesn’t always load)   

Get Support      Work through the screens to get a chat option. 

Apple Support schedule phone call

https://twitter.com/AppleSupport

Assuming you mean activation lock.

https://support.apple.com/en-us/HT201441

As already stated, there is nothing you can do if you do not know the AppleID and password used for activation lock. If the person who sold you that iPhone will not or cannot remove activation lock for you, then you own a device you’ll never be able to use.

If you’re referring to activation lock, you cannot. To enroll or release a device from activation lock requires the AppleID password. The feature would be useless if that were not so.

i bought 2nd hand iphone 6, but it is not activated because of apple id of previous person? so what shall i so to activate my phone and unlock it?