I found a bookmark in my browser that was pointing to a page on my SharePoint 2013 environment (with Project Server 2013) like this http//dev/PWA/TheApp I want to delete this site, but couldn't find it on the Site contents of http//dev/PWA/. So I thought "Maybe it's an App?..." (because Apps are not supposed to appear on the Site Contents). So I went to Central Administration App Catalogue, but as it turns out, the site http//dev/, doesn't even have an App Catalogue... So I thought "Maybe it's a Web part?..." so I went to the Site Settings -> Solutions, but there are no web parts there.
After opening SharePoint Designer and looking into "All files" I saw a folder name TheApp with a aspc file inside it, but the deete button is greyed out and if I click the aspx file I get the warning below:
So... It's not an App, it's not a Web part, and I can't delete it with SP Designer... What is it and how can I delete it?
NB: sorry for any error in understanding the problem but I'm still learning my way around this technology.