For the first, you go to the Header & Navigation section of the Style Properties for your Rekt theme (or a child of it as Themehouse suggest when editing) and then in the Sub-Navigation Row CSS section you put the always handy "display: none;" in the freeform CSS/LESS section.
For the second, are you using TH Nodes addon? It seems you set up custom node icons for your forum nodes. My bet is you did it on the Rekt main theme (again not in a child) and then you didn't click on the "Enable Styling for Style" button on the style you selected, in the "Node layout and styling" section (again if you're using TH Nodes)