I found this picture of the left panel of the Orbiter:
What is the function of that small detachable tube?
That tube was slipped over the nosewheel steering (NWS) selector switch so that the commander could easily find it without taking their eyes out of the window in case of a nosewheel steering failure during rollout.
If the red circle in the picture in the question were a clock, the nosewheel steering selection switch is about at 6:30-7:00. You can see how it doesn't have the mushroom shaped top on it like the BODY FLAP or ENTRY MODE switches near it do.
This shot of page 7.4-20 in the Shuttle Crew Operations Manual will serve as a reference.
The extension was removed and stowed on the Velcro tab as shown in the picture in the question once the shuttle made it into orbit, and was reinstalled for entry. These clips from the Post Insertion and Deorbit Prep checklists show those actions.