What do you mean by plagiarised version? You mean you copued an essay you have previously submitted or it contained non credited work of others?
How long has it been sent? Has your teacher marked it? Why didnt you check what version you were sending? One problem is that if the work is withdrawn you have missed the deadline to submit anything else. See what teacher says on Monday.
Imo whether or not you sign anything, there is still the issue of submitting work that isnt your own.