how to tab backwards a block of code code example

Example 1: how to left tab code in vscode

In Visual Studio and most other half decent IDEs you can simply do "SHIFT+TAB". It does the opposite of just TAB.

I would think and hope that the IDEs you mention support this as well.

Example 2: how to indent the whole block of code in cscode?

you can also indent a whole section by selecting it and clicking TAB.
and also indent backward using Shift + TAB.