Mostly, need of deleting user comes in picture when that user is no longer an employee in your organization. At the moment, UpRaise does not provide delete user option, since the data associated with such users can be useful or organization may need it in future for some reason.
At the same time, it is important to restrict such users from accessing the system if they are not supposed to access it. In such a case, you can only inactivate user. Inactivating user will restrict the user from accessing UpRaise but the data associated with the user will still remain in your database.