Before I download this, since I've had similar issues in the past, do the following checks:
Is the event that spawns the text spawning more than once? You may need a 'Trigger Once' condition. You can see how many instances exist through the debugger (it is possible for multiple instances of text to be created and overlapping each other, giving the illusion that the text is never being destroyed even though it is).
Is the event that destroys the text firing at all? Add an event that destroys something else and see if that other thing gets destroyed. If not, then you know the event that destroys the text isn't firing at all.
If the event that destroys the text is not firing, start disabling conditions until it fires. You should be able to pinpoint which condition is the problem.