You can deactivate users in Freshsales. When you deactivate, 

• The user’s existing records - assigned leads, contacts, accounts, deals, tasks, appointments and notes - are retained.
  
• You will be able to create reports and filter records based on the user.
  
• The user can no longer sign in and access the application. 
  
• The user’s email settings are automatically removed and new emails are no longer tracked. 
  
• Any phone number assigned to the user is reassigned to ‘All Users’.
  
• New records are not assigned to the user. 
  

If you’ve deactivated all the users under a territory, the territory becomes inactive and would not be assigned to any new record. 

When you reactivate a user, the user would receive an email notification after which, the user can sign into the application. 

Since the user’s existing records persist, they can start working on them right away. However, you should assign a phone number to the user (if you had assigned one previously) and the user must sync their email account again to get emails inside Freshsales.