Licensing issue, cannot deactivate the license, cannot find the license info on the website.

Hello, I'm currently using SDL Trados Studio 2019 Freelance Plus.
I'm using it on my two computers and I recently bought a new one and replaced it with an old one. Then, I was trying to deactivate the trados on the old computer, but it keeps failing with the message of "disabled/closed line item cannot be revoked". Also, I tried to find my license information including the license number on the web site > SDL account > Product & Plan > Licenses, but I cannot find anything. What should I do?