DROP ASSEMBLY (Transact-SQL)
Applies to: 
SQL Server
Azure SQL Managed Instance
Removes an assembly and all its associated files from the current database. Assemblies are created by using CREATE ASSEMBLY and modified by using ALTER ASSEMBLY.
Transact-SQL syntax conventions
Syntax
DROP ASSEMBLY [ IF EXISTS ] assembly_name [ , ...n ]
[ WITH NO DEPENDENTS ]
[ ; ]
Arguments
IF EXISTS
Applies to: SQL Server 2016 (13.x) and later versions.
Conditionally drops the assembly only if it already exists.
assembly_name
The name of the assembly you want to drop.
WITH NO DEPENDENTS
If specified, WITH NO DEPENDENTS drops only assembly_name, and none of the dependent assemblies referenced by the assembly. If not specified, DROP ASSEMBLY drops assembly_name and all dependent assemblies.
Remarks
Dropping an assembly removes an assembly and all its associated files, such as source code and debug files, from the database.
If WITH NO DEPENDENTS isn't specified, DROP ASSEMBLY drops assembly_name and all dependent assemblies. If an attempt to drop any dependent assemblies fails, DROP ASSEMBLY returns an error.
DROP ASSEMBLY returns an error if the assembly is referenced by another assembly that exists in the database or if it's used by common language runtime (CLR) functions, procedures, triggers, user-defined types, or aggregates in the current database.
DROP ASSEMBLY doesn't interfere with any code referencing the assembly that is currently running. However, after DROP ASSEMBLY executes, any attempts to invoke the assembly code will fail.
Permissions
Requires ownership of the assembly, or CONTROL permission on it.
Examples
The following example assumes the assembly HelloWorld is already created in the instance of SQL Server.
DROP ASSEMBLY Helloworld;