Hi @suchi01
In the same documentation link you can change version to 6.6.3, it gives you alert.expire option to set the expiration. See below -
Configure triggered alert expiration
By default, each alert trigger record on the Triggered Alerts page expires after seven days. Here are steps for updating triggered alert expiration. These steps apply only to alerts with the "Add to Triggered Alerts" action enabled.
From the top-level navigation bar, select Settings > Searches, reports, and alerts.
Locate the alert that you want to modify under Search Name.
Select Advanced Edit.
Scroll down to alert.expires.
Enter an integer and specify one of the following units: seconds (s), minutes (m), hours (h), days (d).
For example, to set the alert to expire in 3 days, specify 3d.
Click Save.
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