Removing iCloud account from the device settings is the easiest way to disassociate from an iCloud account. But, in case you don’t have access to the device then, follow steps below.
Step 1- Sign in to your iCloud account.
Step 2- Click “Find My iPhone” and wait for the application to attempt to sync with the device you want to delete. If it is unsuccessful, the “Delete” icon will display next to the device name. If it does connect successfully, you must disconnect the device from the Internet and wait for it to appear as “Offline.” Once device is offline click on it to get more options.
Step 3- Click “Remove from Account” to remove the device.
In addition, if you have access to device perform further steps. Otherwise you are done.
Step 4- Tap the “Settings” icon on the device’s menu and select “iCloud.”
Step 5- Move the Find My iPhone slider to the “Off” position.