I had a table User (or I might have named 'Users' rather, but my
recollection is unclear). Since I chose to use devise rather than a
plain user table, I destroyed it.
rails destroy model user
After that, I simply installed and generated devise User, then
implemented migration
If I’m no wrong if you just run the command to generate it again, it will tell you that a user migration already exists. I’m not sure if that’s going to happen (but I guess because you are trying to generate a devise install again)