how unblock my iphone from icloud?

If your phone has Activation lock enabled, the only way to remove the lock is by knowing the AppleID and password for the iCloud account it is locked to. Without that information you cannot disable Activation Lock. If you don't know the password then you need to contact the previous owner and ask them to remove the device from their iCloud account by logging in to www.icloud.com in a web browser. If you cannot contact the previous owner, then you are stuck. Apple will not help you defeat Activation Lock.

Log into icloud.com and remove it.

If you have forgotten your Apple ID information, start here:

https://iforgot.apple.com