I don't really know what you mean, but if you're using the trigger to for example activate a variable
variable=true
you can 'destroy' as in deactivate the variable when the triggers becomes deactivated, by typing in the deactivation field
variable=false
I don't know if deletevehicle works on triggers but you might want to try it and then share the results with us
triggername deletevehicle or was it deletevehicle triggername