Hey CILLIANBILLION

I'm sorry to hear that you've lost access to your Ubisoft account.

To fully unlink a Ubisoft account from your Steam account, you'll first need to regain access to the Ubisoft account currently linked to Steam. The unlinking process can only be completed through the Ubisoft Account Management[account.ubisoft.com] website.

Once you've recovered access to the account, you can manage the linked accounts and proceed with the unlinking process there.

To recover your account, please submit a support case[ubi.li] through our Account Recovery Form and request assistance in recovering your account.

When you submit your case, make sure to provide proof of ownership for your account. This will help our support team verify your identity and expedite the recovery process. Follow the instructions provided by our support team carefully to ensure a smooth resolution.

The following guides with help you in this process:
Recovering access to your Ubisoft account[www.ubisoft.com]
Finding your Steam ID [www.ubisoft.com]
Accessing your Steam transactions history [www.ubisoft.com]