Well I guess the first bit is that you need to destroy the text after some time, maybe put it on a timer? Or depending you could have on clicked instance, destroy text and then create it so you only ever see one.
Trigger once won't work for the second bit because object clicked is already trigger once. You have to lock out the instance as 'used' and you do this with a variable. Variable is set to false, when you click the instance you set it to true, and on the left you add a condition only if variable is false.