declare @Departments table
(DepartmentID int identity(1,1),Name varchar(30));
insert into @Departments values('D1');
insert into @Departments values('D2');
insert into @Departments values('D3');
insert into @Departments values('D4');

declare @Employees table
(EmployeeID int identity(1,1),[First Name] varchar(20),[Last Name] varchar(20),DepartmentID int);
insert into @Employees values('John','Smith',1);
insert into @Employees values('Dave','Johnson',2);
insert into @Employees values('Mark','Andrew',2);
insert into @Employees values('George','Michael',4);
insert into @Employees values('Michael','Peterson',3);

select EmployeeID,t2.DepartmentID,[First Name] + ' ' + [Last Name] as 'EmployeeFullName'
,t2.Name as DepartmentName
from @Employees t1 inner join @Departments t2
on t1.DepartmentID=t2.DepartmentID

Output
---------------------------------------------------------------------
EmployeeID  | DepartmentID  | EmployeeFullName  | DepartmentName
1	      1	              John Smith	        D1
2	      2	              Dave Johnson	        D2
3	      2	              Mark Andrew	        D2
4	      4	              George Michael	        D4
5	      3	              Michael Peterson	        D3

Delete e
from @Employees e 
join @Departments d
on d.DepartmentID = e.DepartmentID 
where d.Name ='D2'