How can already activated and valid product key be deleted from laptop?Answered

Hi, 

Maybe this will be a basic question, but I could not find a solution. 

I am still in development phase, and I want to test my license functionalities.
Therefore I want to delete my already entered limelm test product key from my laptop
(activated and valid) thereby I can simulate the first license window
(with empty product key field) of mine. But unfortunately I could not find a way to reset it.
1-I already deleted my existing libTurboActivate.dylib and TurboActivate.dat files from my application,
and copied clean ones from wyday website but somehow after restart of my app, I am still getting my
old product key. 

2-I tried to enter an empty product key, but as I see TA_CheckAndSavePKey does not save if the key is invalid.

I am totally shocked  :) what can i do to clear my product key from TA?

Thank a lot in advance.