How can I make my computer so that I don't have to put in an unlock code in order to use it?

I have an Acer netbook which is on its last legs. I am going to buy a new one but am trying to wait until the holidays when I can get a good deal.

In the meantime, I have it set up where I need to enter a log in code in order to use it. The past few times I did this, it gave me a weird error message. I’m afraid something’s going to happen where it doesn’t let me unlock it at all.

How can I change it so that I don’t need to enter a code in order to use the computer?