WARNING: You are dropping one or more types that already exist in a database. If the database is later synchronized with ...

WARNING:  You are dropping one or more types that already
exist in a database.  If the database is later synchronized
with the model,  the DROP TYPE statement will succeed
only if all references to the types are also dropped.
If you extracted the entire database into Visio,
then the DROP TYPE statements should succeed.

Do you still wish to drop the type(s)?