Saving changes is not permitted. The changes you have made require the following tables to be dropped and re-created.

This message is faced when you try to make change in table design using SSMS (SQL Server Management Studio). This is default setting of SQL Server SSMS that it doesn’t let user to modify the schema of table and throws the message on saving. The setting is “Prevent saving changes that require table re-creation”. It can be changed through SSMS (SQL Server Management Studio).

• Start SSMS(SQL Server Management Studio)
• Goto Tools Menu and Choose Options (Option Dialog Will Be Opened)
• In Option Dialogue Click Designers ---> Table and Database Designers
• Uncheck the Option : Prevent saving changes that required table  re-creation
• Click Ok

See Following Screen Shot