Cases that are Closed should typically not be flagged. Ensure you've enabled the Automatically Clear Flags on Closed Cases  setting under the Flag Event Rules section in the Case Flags Setup. This will allow you to specify a time frame that Case Flags will go and clear the flags of cases closed for x amount of time.

However, if you need to perform a mass clearing of flags, review the following options.

If you have an active Follow Up Process enabled, please disable the Follow-Up Process before making any mass changes to cases. This can cause a large amount of cases to be set with a follow-up date/time, and re-flag in mass. 

Method 1 (Recommended) – Use Data Loader / ETL Tool:

1. Run a report on Cases with the following criteria:

2. Export the report results to a CSV file.

3. In the CSV file, update the Case Flag Date/Time value of all cases to NULL(), then use Data Loader (or an equivalent ETL tool) to update the records back in Salesforce.

** If you are using Salesforce Data Loader, update the Data Loader settings to enable "Insert Null Values". For additional information on this process, please reference this Salesforce help article. 

Method 2 – Manually clear the flags from a List View:

1. Create a List View which contains the Flag/Flag (BH) fields and the Clear Flag button. See our documentation here for further instructions.

2. Ensure your List View contains the necessary filters for flagged cases you're looking to clear, such as Case Flag Date/Time not equal " "  AND Closed = True.

3. Manually select all of the flagged Cases that you'd like to clear the flag on and click the Clear Flag button.