How to remove selected value in drop-down choices

[katrinamara]

My drop-down has a default value, the default value should not be display in choices when i click my drop-down. And when the user select new value the new value selected should not be seen in drop-down choices and the default value should now be display. Is it possible?

[VatsalJagani]

@katrinamara, I don't understand why do you need this, it looks bit weird requirement to me, how(why) can we remove selected value from drop-down.