where is Web Site Administration on visual studio 2015

I experienced the same issue. You can get to it via IIS or as I did, I copy it to a development folder for future use. Here are two options...

1. Launch the Web Site Admin Tool using a command window:

  1. Open a Command Window running it as a Admin

  2. Change the folder to IIS Express: cd C:\Program Files\IIS Express\

  3. Run the following command to start up IIS Express:

iisexpress.exe /path:C:\Windows\Microsoft.NET\Framework\v4.0.30319\ASP.NETWebAdminFiles /vpath:"/ASP.NETWebAdminFiles" /port:8082 /clr:4.0 /ntlm

  1. Access the Admin Site via the following URL: http://localhost:8082/asp.netwebadminfiles/default.aspx?applicationPhysicalPath=C:[YOUR SITE PATH HERE]\&applicationUrl=/

2. Launch the Web Site Admin Tool using IIS: You can try running the site from the Windows folder but after a couple of issues I just moved it to another folder. The steps below cover that process.

  • Copy the Admin Site from the following folder: C:\Windows\Microsoft.NET\Framework\v4.0.30319\ASP.NETWebAdminFiles

  • Change the web.config to allow any user to access the site

  • Setup the site in IIS. Set the Authentication as shown below. Use the following URL to manage your ASP.NET site.

  • http://localhost/ASPNetAdmin/default.aspx?applicationPhysicalPath=C:[YOUR SITE PATH HERE]\&applicationUrl=/

See the following post at this link