Cleanup unused ApiError codes, update EF docs

docs/misc/dev/upgrade-ef-server-model.md

@@ -8,8 +8,32 @@ nav_order: 6
 
 # Upgrade the AliasServerDb EF model
 
+## Create new migration
 The below command allows you to create a new EF migration based on the existing database structure as defined in the EF mode classes.
 
 ```bash
-dotnet ef migrations add InitialMigration --output-dir Migrations/PostgresqlMigrations
+cd apps/server/Databases/AliasServerDb
+dotnet ef migrations add NewMigrationDescription
+```
+
+When (re)starting the API, any new migrations are automatically applied to the database.
+
+## Remove migration
+In order to remove one or more added migrations, run the following command:
+
+```bash
+dotnet ef migrations remove
+```
+
+> Note: if you get an error stating the migration has already been applied, first rollback the database following the instructions below.
+
+# Rollback AliasServerDb database to previous migration
+
+To rollback the database and undo one or more applied migrations, run the command below and replace the `ChangeDeviceIdentifierToTextfield` with the name of the target migration to revert back to.
+
+So e.g. if target migration is called: `20250922173722_ChangeDeviceIdentifierToTextField.cs` then run this command:
+
+```bash
+cd apps/server/Databases/AliasServerDb
+dotnet ef database update ChangeDeviceIdentifierToTextField
 ```