Well, you are right, it ise annoying until you dislike it. Optimisation of battery is good option though. If you want to remove, you can follow this instruction. Long press on the notification, it will take up to "AdaptiveBrightnessGo" settings, there will be two option, App Icon Badges and Battery Optimised Display, Long press onto Battery Optimised Display, you can see two options, Optmising brightness and Importance, in Importance section, four options are there, Urgent, High, Medium and Low, you need to choose according to your requirements, Low option will remove that notification.
Hope this will do. Give me feedback