Hi @pauIbanez,
Since you no longer have access to the other site or team settings, our Support team can remove the link between this domain name and the other Netlify site/team - provided you can verify ownership or control of the domain.
We have a guide in our Support Forums that explains how to create the verification record here:
If the verification TXT record is created, our support team will be happy to delete the configurations for this domain from the other account.
Please let us know when you have created the TXT Record so we can verify. Thanks!