Prevent events from removing after deleted record

No, you cannot preserve Record Events when hard deleting a record - they're automatically removed. Use soft delete instead: add an isDeleted field, write the deletion event, set isDeleted = true, and use a sync filter to hide the record. This keeps the audit trail intact.

https://docs.appian.com/suite/help/25.2/Delete_Records_Smart_Service.html

Where would you display that event record? What is the underlying use case here?

Since record event relate to record using the primary key of the parent record, you shouldn’t remove the parent record. Its better to set status of record to “Removed” instead of removing the record from table so that the record event can be set as per requirements and has links to arent record.

alternatively instead of status as Deleted  or Removed, you can configure a separate column to store 1/0 based on whether record is removed or not!