It is difficult to reproduce exactly the problem. But with build544/Vista I can now delete the new templates I ceated, but not the oldest. And I succeeded also to delete the first created, but only after I have created a new one. And now, the last created remains... So it seems I have not understood what I have to do to delete a template.
Here is what I do : I create a template (CT) by clicking [Add]. Then I enter some text and I click [Apply] then [OK]. I quit HE. Then I open HE. The CT created work fine. I try to delete the last created CT by selecting it then clicking [Delete] then [Apply] then [OK]. The CT disappears, no error message. I quit HE. But when I re-open HE and /Tools/Options/Syntax, the CT I had deleted is always there and... it works fine.
In some circumstances I can delete some CT, sometimes the first created, and once (only once, but I don't know how I made that) the last creatd CT was really deleted (ie not there when re-open HE). But even when I deleted cleanly the last created CT, some anterior CT didn't want disappear. So I have always at least one CT in my list.
All those operations were realized directly on XML templates, without have opened other syntax setting.
Which types of document you have opened before trying changing templates? (XML, HTML, VB ..)
Today XML only. I have tried also to delete the html CT I had created in XML and inherited from XML. There also, the CT seems dead, ie it doesn't appear neither in XML nor in Html. But when I re-open HE, they relive. Frustrating, isn't it ?