westwoods you are trying to re-run a migration you created yourself ?
If you are in a development context and the migration is part of your own extension (do you say you put it inside the Tags extension?), you can revert all migrations of your extension by running php flarum migrate:reset --extension=vendor-name. This will run the down function of every migration defined in that migration. Running php flarum migrate afterwards will run all the up functions again.
If you manually deleted a table/column and want to run a specific migration again, you can delete its entry from the migrations table. Make sure your database is ready to run the up function of that migration again. If it tries creating columns or tables that still exist you will experience errors.
