The factory default CodeLock code is "0000."
When you enter the code lock setup, you need to enter the correct code (4 second hold down of two left hand buttons then press the left hand button once).
Once you have entered the correct code, you can change the parameters of how the codelock system will operate.
You can also select codelock "off". Select code lock “off” and press and hold the two left hand buttons to save this as the new setting.
This should all be covered in your ST50 Series Instruments Owner’s Manual, available here:
➥ Raymarine Marine Electronics - Retired ST50 Manuals