I deleted the exported zip file that was placed in my exported templates folder and of course it still shows in Visual Studio\'s \"Add New Project\" dialog. I expected that but
I was able to solve this problem for my Visual Studio Community 2017 by first deleting the template zip files in the following folders:
%UserProfile%\Documents\Visual Studio 2017\Templates\ProjectTemplates
%UserProfile%\Documents\Visual Studio 2017\My Exported Templates
Then deleting the following folder:
%UserProfile%\AppData\Roaming\Microsoft\VisualStudio\15.0_aed38a72\ProjectTemplatesCache
(The identifier after "15.0_" might vary)