Though I didn't set up an official trial period, at the end of 3 weeks it seems like we do not have a "good fit." How do I actually terminate (letter vs. in-person)?

If in letter, do you have some basic example to share?

If in person, do you do it at dropoff/pickup, Monday/Friday, etc...? What to say?

I don't know if there's any point giving a 'warning' since I think it's just not a good fit rather than resolvable specific issues, but don't want to have it come out of the blue.

Thoughts?