Unfortunately I'm stuck in the file selection screen.
First of all you really should think about your project structure.
You have about 100 Events just to select a letter. You could change that by giving the letters instance variables. Or why don't you already just position them in the construct layer? (and use different layers).
To avoid huge events like event Number 192 you may also add another instance variable to see in which row the letters are.
I assume you want to reduce the text string by one letter, when the user hits the button backspace. Try to use RamPackWobbles Function.
Whenever the user hits a letter check this.
Compare two values len(Text.text) > 6 ... error or something else.
RamPackWobble: He uses a Sprite that's called backspace.