You can't. JIRA won't let you destroy that audit information.
Just make the user inactive so that they don't count towards your licence usage (and I tend to remove them from all groups and roles, change their name to something to indicate they've left, and set their email address to a null mailbox)
If you want to delete, one approach would be to bulk delete the comments and all information associated to this user in the database, however, this is not recommended nor supported, and it would destroy audit information
The best approach would be making the user inactive as Nic mentioned.
I’m a designer on the Jira team. For a long time, I’ve fielded questions from other designers about how they should be using Jira Software with their design team. I’ve also heard feedback from other ...
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs