You could create the user again with the same username.
But i presume that you do not need that user to manage the issues anymore, so you could just create a filter like
assignee = username
and perform a bulk change and edit the assignee to someone that still exists in Jira.
Once your Atlassian account is permanently deleted, you can’t restore your account. Before we permanently delete your account, you’ll have a 14-day grace period, during which the account will appear as temporarily deactivated. You have until the grace period is over to cancel the deletion.
Please check the following article: Delete your Atlassian account
Thanks for accepting this answer if it resolves your question.
Hi everyone! Are you interested in beta testing Atlassian University’s newest (unreleased!) training course? We’re looking for 15-20 volunteers to test our newest training course, Basic reporting...
Connect with like-minded Atlassian users at free events near you!Find an event
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no Community Events near you at the moment.Host an event
You're one step closer to meeting fellow Atlassian users at your local event. Learn more about Community Events