we have to uninstall the 4.5 which comes under the Server roles not features. I am also attaching screen for the reference.
For this open the Server manager -> Dashboard -> 2) Roles and Features and follow the following steps which are mentioned in screenshots.
Note: I am showing you how to Add Roles and Features wizard (install new features/roles) but if you want to uninstall/remove (uninstall new features/roles) then you have to click on “Start the Remove Roles and Features Wizard”. Please make sure that, first we have to install IIS and then .NET framework.
Select the server
You have to check ASP.NET 3.5 and ASP.NET 4.5 (based on requirement) options for register the .NET framework with IIS.
To install any features/roles, we have to check that option which we want to install. For uninstall any features/roles you have to uncheck it.
Please find the reference links below.
http://www.iis.net/learn/get-started/whats-new-in-iis-8/iis-80-using-aspnet-35-and-aspnet-45
http://www.iis.net/learn/get-started/whats-new-in-iis-8/installing-iis-8-on-windows-server-2012