Can I find log activity of who deleted a user and who edited an entry?
Craft only stores minimum audit information in the database... mainly just when a row was created and last updated.

If you're on Craft 2, there is a deprecated Audit Log plugin which might do what you're looking for.

I don't think the author has intentions of porting it to Craft 3, but there is a commercial plugin called Audit that is in the Craft Plugin Store.