I have LR 6 on my desktop and laptop (as the license allows). Just got a new laptop and uninstalled from the old laptop but now I get the error that I have to deactivate a computer before I can activate on my new machine. How can I deactivate an instance that has already been uninstalled? Thanks!
Seems that your activation limit has reached two and you did not sign out from your old laptop before uninstalling so that is still in count.
You will have to install it again on your old laptop and go to help menu and choose sign out or deactivate from there.
Then, you will be able to able to install it and activate it on your new machine.
If you do not have your old laptop or if this process is not possible for you, you can send me a private message with your email address so that I can update the records from backend.