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
To allow saving the modification they suggested that first drop the table and then recreate it which is not suitable when you have important data/information, and it also causes increase in rework.
To save yourself from this rework, we have another way which is mentioned below.
Step 1:- Open your SQL Server Management Studio.
Step 2:- Goto Tools -> Options -> Designers.
Step 3:- Uncheck checkbox "Prevent saving changes that require table re-creation".
Step 4:- Save your changes.
Now, attempt to save your modification changes which you have done in your table.
I hope that this will work for you as it worked for me. So please leave a comment if this post help you so other visitors can also trust on this solution.