are these toads native to Thailand or are they introduced ? they look very much like cane toads back home ...

Do you want to kill the toads? If so this is the humane way. Place the toads in a container with air holes and put in the fridge overnight. This puts them into a natural sleep mode. Next day put the container in the freezer for 2 days. Dig a hole and bury. Job done.

Why do you think there is just one toad? My house isn't even very rural and I have tons of them. After a heavy rain I can't even hear myself think with their noise