Hello @Sergio_Anibal_Agudelo_Correa ,
Welcome to The MongoDB Community Forums! 
The error message you are seeing indicates that the user you are logged in as does not have sufficient privileges to execute the updateUser command or the changeUserPassword method. Please confirm the role assigned to the user attempting to perform the updateUser command.
Note: You can check the roles assigned to your user by running db.getRoles() command.
Additionally, could you confirm whether or not this is an Atlas deployment and if so, what is the cluster tier? For reference, the M0 free clusters and M2/M5 shared clusters don’t support the updateUser command as per the Unsupported Commands documentation.
Regards,
Tarun