In SQL Server 2008/2012 the default table designer behavior is to disallow you from saving changes to table that require the designer to delete and recreate your table. In SQL Server 2005 SSMS the default setting allowed you to save your change by acknowledging a message prompted. If you’d like SSMS 2008 or 2012 to behave the same way your SSMS 2005 did, just follow these simple steps:
1. Open SQL Management Studio
2. Click menu Tools > Options
3. In the Options window click Designers
4. On the right pane, uncheck the checkbox that says Prevent saving changes that require table re-creation
5. Click the OK button
You should be all set at this point. Test it out by opening the table designer, making your changes, and saving them.