Can't raise a purchase invoice in a locked period

Hello
Thank you for your quickly reply
I have appointed one of your accountants to do the my first filling return as limited company ,
He ask me to do the bookkeeping , therefore I have to
to input all my sales and purchases, some dated for few years before to activate my comany that has been dormant for a while,
Later, one I have done this task my self he will do the returns for the first time
I thinks that probably I can delete any journal as long this not delete my date of course,
Thank you for your comments
Maria