Trivial example:
Command "say /zones" will create some triggers and command "say /removezones" will delete these triggers.
But I want to create a plugin wherewith I can detected where is some player. (If some player type in chat "/where" the triggers will be created, will be show some message in chat with player's position and I want after to delete triggers because the map will be full with triggers and the server will be lagged.)