Recommend contacting Winnebago, they can probably tell you how it is installed plus forward you the drawings of the wall, which will help you install the new TV.
But my best guess would be the shelf is screwed to the wall and maybe the screw heads are covered with plugs.
2002 W-22 266"wb, Winnebago Chieftain 39T, UltraPower, Koni's, Helwig bars, Nuvi 660, Sirius, Scan Gauge II, Sentry TM. 2003 LW300 Saturn toad, Sterling towbar & Apollo brake. And Hannah the Princess and Stevie the Dude!