Can I reorganize a Primary Key after deleting some rows?
Both options delete all records from your table and restarts IDENTITY values.

TRUNCATE TABLE

TRUNCATE TABLE &lt;schema&gt;.&lt;table_name&gt;;



  Removes all rows from a table or specified partitions of a table, without logging the individual row deletions. TRUNCATE TABLE is similar to the DELETE statement with no WHERE clause; however, TRUNCATE TABLE is faster and uses fewer system and transaction log resources.


or

DBCC CHECKIDENT

DELETE FROM &lt;schema&gt;.&lt;table_name&gt;;
DBCC CHECKIDENT ('&lt;schema&gt;.&lt;table_name&gt;', RESEED, 0);



  Checks the current identity value for the specified table in SQL Server 2017 and, if it is needed, changes the identity value. You can also use DBCC CHECKIDENT to manually set a new current identity value for the identity column.