How to Reset Stuck Vehicles

Two ways: First is to get into the stuck vehicle (easiest way to do this is via [TAB/R3]) then open the map, select one of your vehicle sheds and press [F/X] to teleport.

If you have the drone available, you can fly over one of your sheds and reset vehicles that way.

If your vehicle is stuck in water you can return it to a shed using Functionalities > Recovering vehicles on the tablet.