Disable lock code e71 Nokia

Hello, I have been in possession of a Nokia E71 for a year now, which works very well. For privacy reasons regarding my friends and family, I activated what they call the "lock code" on this phone. This code allows the phone to lock with a code after 1 to 20 minutes, depending on the user's choice. To disable this code, you simply need to select "none" in the part where you choose the lock time instead of setting the time yourself. The problem is that when I select "none," my Nokia displays an error message saying "unable to unlock the phone." Do you have a solution for this, please? I want to emphasize that this is not a stolen phone since I have access to it, but the fact that I have to enter a code every time my phone has been inactive for more than 20 minutes is starting to annoy me.
Thank you in advance for the help that I hope you will provide.