Hello, and Welcome to Android Central!
Sorry your having this issue! Is this the 3rd Party App Lock from the Play Store? Either way, you'll need to enter the setting of App Lock and look for security settings, or anything that indicates a password sections. You'll need to deactivate it from there, you'll be required to enter the 4 digit PW in order to deactivate/disable.
Also, if its the one i'm thinking of, there should be a setting from within the "settings" section, that allows the password to remain, until you hit the sleep wake manually or it does a time out.
Let me know if this helps!
Chris