Thanks for using Bitnami. You can get more information about how to remove the Bitnami banner in the link below
Apart from that, can you give us more information about your issue? What did you try to remove it? We have a Support Tool that will gather relevant information for us to analyze your configuration and logs. Could you please download and execute it on the machine where the stack is running by following the steps described in the guide below?
How to Run the Bitnami Support Tool
Please note that you need to paste the code ID that is shown at the end.