OTP -Memory Location

This information is in the Reference Manual for your stm32, in this case RM0368. It is in section 3.7 "One-time programmable bytes"

I won't give you an extract of the page because I think it would be much more useful for you long-term to download the RM and go to the page yourself. I do wonder how many people struggle with stm32 because they don't have the Reference Manual, perhaps just trying to use the HAL calls following stm32cube examples, but no understaning of the underlying hardware and its amazing capabilities.