Authentication Issues in Salesforce

Hi Neha,

Please try to Remove an Account from Salesforce Authenticator (Version 2 or Later).

• Begin in a web browser, in your Salesforce account. From your personal settings, enter Advanced User Details in the Quick Find box, then select Advanced User Details. No results? Enter Personal Information in the Quick Find box, then select Personal Information.
• Find App Registration: Salesforce Authenticator, and click Disconnect.
• Open the Salesforce Authenticator app on your mobile device.
• In the app list of connected accounts, find the account you want to remove.
• Swipe left on the account username.
• Tap Remove or Delete, whichever appears.
  A confirmation dialog appears.
• To confirm the removal of the account, tap Remove.

Hope this helps you.