how to remove iCloud account without password

Greetings alikhomacuphe, 

Your question can lead us in a couple directions and we’ll provide two options for you. Should there be additional circumstances, please let us know what they are, but typically these would be the two options at your disposal without knowing the Apple ID password.

First, if the Apple ID that is signed in on the device is yours, then you can reset the password. The following article is going to go over how to do that and shows the process from a variety of places such as on an iPhone/trusted device as well as the web - If you forgot your Apple ID password 

If for some reason resetting the password is not an option and you are the original owner of the device and have proof of purchase, you can request removal of the iCloud account using the following link - Activation Lock - Support

Please keep in mind a few things, and these are listed on the request before you make it and are directly from Apple - Additional Support - Activation Lock

You must be the owner of the device.

Proof of ownership documentation is required. Proof of ownership must include the product serial number, IMEI or MEID.

Your data on the device will be erased.

If Apple unlocks Activation Lock on your device, all files and data stored on your device will be permanently erased. Please note, restoring your device from a local backup will re-enable Activation Lock.

We can’t unlock a managed device.

If your device is owned by a business or educational institution, please contact your IT department or manager. We also do not accept bulk requests.

Your device must not be in Lost Mode.

Thanks.