how can I reduce my project size in Visual Studio

When ever you create any project using Visual Studio, it adds so many files by default as it is part of Project Template that you selected to create project. Now it depends, whether you used those pages for your requirement or not. E.g. Login, Register User and their DB schema added by default by Visual Studio. If you think all these files (including web pages, .mdf, .ldf, .js, images etc) are not used as per your requirement. You can remove those files. Also try to publish your site, it will also remove some files which required only for development not deployment.