Most DIN and Double DIN sized radios either have a removable trim ring that pops off to reveal screws holding it in… or more common you slide special removal tools down both sides to release hidden anchors.
Look for the Installation Manual online for your radio model to determine which kind you have. If your RV came with a bag full of manuals your instructions might be in there. It’s even possible the radio bag even has the removal tools included in the bag.
When in doubt take your RV to a local car audio installation shop. These thing are fairly standardized and not unique to your RV.
2017 Winnebago Adventurer 37F
2016 Lincoln MKX Toad