Create a new user/login in sql azure with access to read/insert/update on the database items like tables sp,view etc.
This user will not have the permission to drop
please read this article from Microsoft on how to properly create logins, users and assigning access rights in SQL Azure: Managing Databases and Logins
Then, in order to assign or deny specific permissions, review this article from Microsoft as well: Granting Access to a Database Object
And here is the link to specifically deny access to permissions: Deny Object Permissions
Note that you can also apply permissions to schemas. A schema is a container of database objects on which you can assign permissions. So you could easily place all your stored procedures in a single schema that you created to that effect, deny alter/drop permission, and grant execute on the schema directly. This way, all the objects within that schema will inherit the permissions defined. Here is the article for schema permissions: GRANT Schema Permission