How to re-classify a Primary Residence as an Investment Property for 1031?

[Takahito Torimoto]

If I had an investment (STR) property for 2 years (We'll call it property A), but then moved into it full-time (not renting it out) "converting it" into a Primary residence - and in the future, I decided to purchase and move into a different Primary Residence (we'll call this property B) - what's needed to be able to do a 1031 on property A? i.e. Do I need to rent it out on AirBnB or VRBO for a set amount of time?  Or can a 1031 be done with property A immediately (or a few weeks) after we move into property B?  What is the trigger that allows me to officially claim property B as "Primary residence" and how can property A be re-classified as "Investment Property" for the sake of IRS/legal/1031?

Thanks for any help in advance!