If you want to re-enable Entity Framework code generation, open the EDMX file in the EDM Designer, and on the property sheet, set “DevForce Enabled” to false, and save the file. This action:
You will also need to set the Code Generation Strategy to Default to generate an ObjectContext-based model. EF 5.0 uses the DbContext generation template by default.
Remember to reset the “DevForce Enabled” flag back to true to re-enable DevForce code generation.
You can also globally disable DevForce code generation by going to the Visual Studio menu and selecting Tools -> Extension Manager and disabling the DevForce EDM Designer Extension.