How to disable "Completion time:..." in SQL Server Messages window
In SSMS 18.3, they added the option to turn off the completion time.
Tools > Options > Query Execution > SQL Server > Advanced.
Uncheck the Show Completion Time checkbox.
Start a new query window and execute something... No completion time after query finishes. Yay!
The completion time message was added in SSMS 18.2
https://cloudblogs.microsoft.com/sqlserver/2019/07/25/sql-server-management-studio-18-2-is-now-generally-available/
I don't believe there is a way to turn it off