Revoke and Grant Privileges on SQL Server Database
REVOKE means is taking the privileges back. If you didn't give any permission to any user, you can not take a back.
You can use DENY, but not on the DROP and TRUNCATE. There is not a DROP and TRUNCATE permission just like you wrote.
DENY DELETE, UPDATE, INSERT ON DATABASE::[databasename] TO user1;

But, you should think about the privileges which are you want to grant and check out the database roles.