How to drop all tables in a SQL Server database?

It doesn't work for me either when there are multiple foreign key tables.
I found that code that works and does everything you try (delete all tables from your database):

DECLARE @Sql NVARCHAR(500) DECLARE @Cursor CURSOR

SET @Cursor = CURSOR FAST_FORWARD FOR
SELECT DISTINCT sql = 'ALTER TABLE [' + tc2.TABLE_SCHEMA + '].[' +  tc2.TABLE_NAME + '] DROP [' + rc1.CONSTRAINT_NAME + '];'
FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS rc1
LEFT JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS tc2 ON tc2.CONSTRAINT_NAME =rc1.CONSTRAINT_NAME

OPEN @Cursor FETCH NEXT FROM @Cursor INTO @Sql

WHILE (@@FETCH_STATUS = 0)
BEGIN
Exec sp_executesql @Sql
FETCH NEXT FROM @Cursor INTO @Sql
END

CLOSE @Cursor DEALLOCATE @Cursor
GO

EXEC sp_MSforeachtable 'DROP TABLE ?'
GO

You can find the post here. It is the post by Groker.

You can also delete all tables from database using only MSSMS UI tools (without using SQL script). Sometimes this way can be more comfortable (especially if it is performed occasionally)

I do this step by step as follows:

1. Select 'Tables' on the database tree (Object Explorer)
2. Press F7 to open Object Explorer Details view
3. In this view select tables which have to be deleted (in this case all of them)
4. Keep pressing Delete until all tables have been deleted (you repeat it as many times as amount of errors due to key constraints/dependencies)