Here you go.
Unlinking a soldier from your profile / Origin account:
This must be done through customer support as you cannot do this for security reasons. Please note that ALL stats/unlocks/progression will be reset permanently for the account that gets unlinked, other accounts linked will remain fine and untouched.
http://answers.ea.com/t5/Battlefield-4/READ-FIRSTS-Common-issues-Fixes-amp-Guides/m-p/3218167#U3218167
- Permanently delete your EA / Origin Account
For security purposes, it isn't possible for players to close an Origin (EA) account themselves. In order to delete an Origin (EA) Account, players will need to contact one of our Game Advisors, who will be happy to assist them. Please be aware that for security reasons, when you speak to a Game Advisor, you'll be asked a number of questions to verify account ownership.