How can I remove "aswelb/2.0" in the HTTP Response Header?

Note AWS team this is being reported by Penetration Testing firms as an information disclosure vulnerability. Request that action is taken to address..

Unfortunately, there is no option to remove the header at this time. If you deploy 3rd Party Solution like F5 WAF, you can cloak server information.

It's not customizable at the moment. A workaround would be to front the ALB with CloudFront and use edge functions to override the Server header with none, as briefly illustrated here: https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/lambda-examples.html#lambda-examples-overriding-response-header