The apps don't know. That's the whole problem. The photo service will build a cheerful slideshow of "this day, three years ago." The birthday reminder will fire. Their account will "suggest" you say hello. Each one is a small ambush built by software that thinks memory is content.
Softening the ambushes
- Photo apps: look for settings to hide a person or date range from 'memories' features - most have one now, buried
- Mute their chats rather than deleting them; muting keeps the archive without the surprise
- Turn off the birthday-reminder layer in your calendar apps, or replace it with your own entry, on your terms, in your words
Their accounts - only when you're ready
- Most platforms offer memorializing (the profile stays, marked, frozen) or removal; memorializing is reversible in spirit - deletion isn't
- There is no deadline. An account can wait years. 'Not yet' applies to the internet too
- Save-what-matters first: photos, voice notes, the message threads you'd grieve losing twice
One more thing, gently: their old messages are a room you can visit. Some people find comfort there; some come out flattened every time. Notice which one you are, and visit accordingly.