>>General warning!
>>When you do a table modify,
>>you can destroy the db structure or lost data.
>
>Is the setting in regards to that is "Prevent saving changes that require table re-creation"? That is the only one I remember having changed. However, it does not say it has an impact on removing a field and blocking its removal if it has an index. In my case, it works. For another person, he has the warning and cannot proceed.

Table re-creation is necessary in some cases.

The fundamental problem is that the scripts builded by SSMS
are not contained in a single transaction,
with a rollback when it fail..

When they fails, a part of the transaction remains in the database.