tabbar doens’t provide such a built-in functionality. However, there is “close” button feature dhtmlxTabbar/samples/06_behaviors/01_closing_button.html
Image is place after the text and removes tab on click. You may disable this behaviour by event handler and show any other image instead of “x” (but only one image).
The other image can be added as part of the text (you may try to attach html as tab label)