Saving changes is not permitted. The changes you have made require the following tables to be dropped and re-create. You have either made to a table that can’t be re-created
or enabled the option prevent saving changes that require the table to be re-created.

When you want to change or add-remove rows on your table that you have already created. The changing is not permitted by default.

You can solve this problem with 2 ways. First one you can drop the table and make changes after than you can undrop table again.

But i want to show diffrent solve for this problem. You can change this option on SSMC permanantly.

Sql Server 2019 Management Studio Saving changes is not permitted

1- Go to management studio Tools / options settings

2- Go to Design Tab an uncheck prevent saving changes that require table re-creation checkbox.

You can change and saves your rows on Sql server anymore.