Certainly, there are some solid anti-theft systems out there, but for the folk who might not have the financial resources to afford one, or the need for daily protection, what I'm proposing is a no cost action that might provide temporary protection when heading for a day trip to the big city or a road trip down the east coast.
For the sake of argument... (and my position is weak, only using Google and some nerd power) In removing the battery from the fob you've eliminated the broadcast capability of the code. I don't think deleting and making a new fob is feasible without an initial piece of code from it. With the battery removed, the fob chip now relies on a weak electro-magnetic field produced at your dash button to communicate.
Unless someone can get close enough to you, or has an antenna powerful enough, your code is now secure. (...is that a cell tower hangin' outta yer ***, or are you just happy to see me)
Apparently the devices that can capture, copy, and manipulate the code are cheap and plentiful.
For me, it's a piece of mind that the truck (with ma's knitting and pa's glock in it) might still be there after me 'n ma have taken our pee break at the Clara Barton rest stop on our way to visit family down south.
Us old retiree's worry about stuff like that.