Saving Changes is not permitted, the changed you have made require the following tables to be dropped and re-created

Saving Changes is not permitted, the changed you have made require the following tables to be dropped and re-created. You have either made changed to a table that can't be re-created or enabled the option Prevent saving changes that require the table to be re-created

You may get the above error while modifying the table design in SQL 2008 or SQL 2012.

Solution
1) Open SSMS
2) Tools - Options
3) Designers -- Table and Database Designers
4) Uncheck Prevent Saving changes that require table re-creation