How to Remove the Witness from a SQL Server Database Mirroring Session

Transact-SQL:
To remove the Witness from a SQL Server database mirroring session using T-SQL, run this code from either database mirroring partner:

ALTER DATABASE [Database_Name] SET WITNESS OFF

mirroring_set_witness_off_tsql

SQL Server Management Studio:
To remove the Witness from a SQL Server database mirroring session from SQL Server Management Studio:

Connect to the principal server instance -> Right-click the database -> select Tasks -> click Mirror:

mirroring_remove_witness_ssms_1

Delete the Witness network address from the Witness field:

mirroring_remove_witness_ssms_2

And click 'OK' to confirm:

mirroring_remove_witness_ssms_3