You should (although it may be hidden in some scenarios). There are two things to consider:
You are basing your design on the current presentation - that's a reasonable thing to do, so long you remember that the presentation might change on other devices, like, say, a mobile phone.
On a mobile phone the tabs may be collapsed under a menu, in which case they won't provide a visual indication to where the user is.
Again, you are basing your design on presentation. But one recommendation is to first design the content and structure of the interface (as would be read by a screen reader) only then deal with presentation.
In such a case, the menu may be skipped, so you'd still need the heading. What's more, blind people often search for headings. So there is an accessibility compliance involved here (you could have the heading on the page, but hidden - will still be read by screen readers).