What is this icon & how to remove it?

[Steveold]

What is the icon arrowed, it suddenly appeared, it looks like a battery, but as you can see I already have that.

 

[Hadron]

It means you have power saver on. Or at any rate, that's what the power saver toggle on my Samsung tablet looks like, and the icon is on the right, suggesting it's a system notification rather than an app, so I'm fairly confident that's the case.

 

[Steveold]

Many thanks. Sorted