How to unlink anonymous EA account and link my actual EA account?

See this info guide

Simple answer is you cant, the EA account linked to the swtor account if the account was created after 25th June 2019, only exists for swtor billing, you do not have access to that account.

If the account was created before 25th June 2019 you can access that account, however account linkage is permanent so it cant be changed , these accounts can use different emails and passwords as the email does not govern the linkage