[Basssiiie]

You can spawn trains (and other vehicles) at any time with AddStaticVehicle and AddStaticVehicleEx, unlike the Wiki states. You can also destroy those vehicles again with DestroyVehicle, if I remember correctly. (I need to check that though, to be sure.)

The error might be caused if you try to delete static vehicles which still have players in/on them, or you just can't delete trains, or both.