How to remove icloud from iso without password

Hello Babu Junior,
I believe you are referring to Activation Lock on an iPhone. If that is the case, you will need to know the password or the person that knows the password to get pass this security features. Take a look at the article below for more details about Activation Lock and how to turn it off either by signing out on the device or on iCloud.com.
Turn off Find My iPhone Activation Lock
https://support.apple.com/en-us/HT201441
Take care