In Solution Explorer, select the project.
On the View menu, click Property Pages.
Click the Build or Debug tab, in a Visual C# or a Visual F# project, the Compile or Debug tab, in a Visual Basic project, or Configuration Properties, in a Visual C++ project.
In the Configuration drop-down list, click Debug or Release.
Try this...
for more clarifications on this refer from below article...
http://www.dotnet-tricks.com/Tutorial/visualstudio/N799060712-Visual-Studio-Debug-VS-Release-mode.html
Rajesh B
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