It is recommended that  a good backup is performed before purging any data.

see here:

Remember that Data Deleted using this process is deleted permanently and NOT recoverable.

The following are deleted in the purge: The Person and their related objects: License, Passport, Business card, PIV, photo, Agreements and signatures, Visits, Pre-Registrations, Access Cards, etc. 

On a client, Home > Configure > Database Tools > Click Delete Person Data > input number of Days to Delete Records older than > hit Delete

with the settings above it deletes any data older than 365 days from the deletion date.

If today was 6/3/2024, this leaves you with 365 days worth of data from 6/3/2023- 6/3-/2024