When installing a new instance of SQL Server, there is a setting that needs to be updated in order to freely make changes to tables and save those changes. Until making this setting change, you are limited to what database schema changes you can make. Here is the error you will receive if you try to update your table schema:
“Saving changes is not permitted. The changes you have made require the following tables to be dropped and re-created. You have either made changes to a table that can’t be re-created or enabled the option Prevent saving changes that require the table to be re-created.”
In SQL Server Management Studio select Tools > Options > Designers
Uncheck “Prevent saving changes that require table re-creation”.