in blogger template we cannot remove powered by blogger gadget from our blog because blogger template designer lock it. but i share with you how to remove blog attribution from blogger
1) go to blogger dashboard and click on template
2) now click on edit html
3) use Ctrl+F and find attribution

4) now see above given image where you seeing this words attribution ,locked"true" change these true word into false  
5) finally click on save template and go in layout and remove attribution gadget from your blog