Follow the arrows in Microsoft SQL Server Management Studio to change the recovery model to simple.
If you also nee to clean up the transaction logs see this question:
https://www.qvera.com/kb/index.php/541/how-shrink-sql-server-transaction-logs-for-the-qie-database?show=542#a542
Also see these related questions
How to shrink MS SQL Server transaction logs for the QIE database?
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