I’m a little unclear what you mean by “But my manager need evidence to show those testing that I had done previously.”
As long as you have not run the "audit trail cleaner’ then the deleted action history does exist in the SQL DB, so you should be able to run a report against that.
Also, what version of the root server are you running?
The actions and if they are deleted are stored in: [BFEnterprise].[dbo].[ACTION_FLAGS] and info in [BFEnterprise].[dbo].[BES_ACTIONS]
It would be useful if there was a nice DB view / report built in for deleted actions.