In You Only Live Twice (1967) M hands a note to 007 containing the address and name of the target Bond's supposed to meet in Tokyo. Instead of telling him these details, they are written in a piece of paper and when 007 receives it, he immediately uses his lighter to burn it after taking a glimpse at it. Why? Is he following protocol or is this an exaggeration to secrecy for something that seems unnecessary here? I don't remember seeing this ever again in a Bond movie.
Seems like a security protocol. He works for secret services, all the information he leaves behind can be a risk.
Self destruct messages, removing signs and burning paper message is a common trope in spy films.
Refer This Page Will Self-Destruct trope for details.