When you delete an assembly instance, all elements within the assembly are deleted.
If you delete the last instance of an assembly type, the type will also be deleted.
When you delete an instance for which assembly views have been created, the views will be deleted from the project unless you first transfer them to another instance of the same assembly type, as explained below.
When you delete an assembly type, all instances of that assembly are deleted as well as any associated assembly views or sheets.
To associate assembly views with a different assembly instance
- In a project view, select the assembly instance you want to acquire the assembly views. Note that the instance must be of the same type as the instance with which the views are currently associated.
- Click Modify | Assemblies tab
Assembly panel 
(Acquire Views).
To delete an assembly instance
- Select the assembly instance in a project view.
- Press Delete, or click Modify | Assemblies tab Modify panel
(Delete).
To delete an assembly type
- In the Project Browser, under Assemblies, right-click the assembly name, and click Delete.
- When prompted that deleting the selected assembly type will delete all its instances, click OK.