To reset an identity column in SQL Server, you typically use the `DBCC CHECKIDENT` command, which allows you to reseed the identity value. This is especially useful after you delete rows and want to reset the identity back to a specific starting point. The basic syntax for this command is `DBCC CHECKIDENT (‘table_name’, RESEED, new_value);`, where `table_name` is the name of the table containing the identity column, and `new_value` is the value you want to set the next generated identity value to. For example, if you have a table called `Employees` and you want the next identity value to start from 1 again, you would execute `DBCC CHECKIDENT (‘Employees’, RESEED, 0);`. Note that setting it to 0 means that the next insert will produce an identity value of 1.

It is important to ensure that the new seed value does not conflict with existing values in the identity column to avoid primary key violations. If you want to reset the identity column after truncating a table, consider using the `TRUNCATE TABLE` statement, which automatically resets the identity seed to the initial value. However, be aware that `TRUNCATE` cannot be used if foreign key constraints exist; in such cases, you might have to use `DELETE` statements followed by `DBCC CHECKIDENT` to achieve the same result without violating constraints. Make sure to thoroughly test these commands in a development environment before executing them in production, as they can lead to data loss if not used carefully.