Disable "save" prompt in SQL Server Management Studio 2005
The feature doesn't exist, but you can vote for it here.
In SQL Server Management Studio 2016
you can unchecked the Prompt to save unsaved T-SQL query windows on close
:
The option is under the Query Execution\SQL Server\General
sub-menu.
Once unchecked, the annoying prompt for saving is disabled.
There isn't an off switch - currently!
Microsoft are reluctant to add one, but you can perhaps join the growing throng of people who are trying to persuade them:
prompting-for-modified-windows-when-closing-ssms-should-be-optional