This guide is about how to reset 2FA settings for a certain user. In case when user lost all devices (phone, U2f device or access to his one-time secret password).
Step 1. Go to Jira Administration tab and select Manage app section.
Step 2. On the left side menu panel find “2FA FOR JIRA: U2F & TOTP” tab and click User Management.
Step 3. Type at least 4 letters to search user by username.
You will see all users (username with email address) based on username which you type. Find user in dropdown list and click Reset.