The "Powered by Blogger" attribution below all blogger blogs, is added by blogger, this can not be remove from the template layout because it is automatically locked by blogger, but this can be done after you edit the attribution tag from your template.
If you edit the attribution link from your template layout, it will provide no remove link, but the remove link will appear after editing your template, compare the image below, before and after editing your template.

How To Remove The Attribution
- Go to your blogger dashboard
- Click on "Design" > "Edit HTML" > "Expand Widget Templates"
- Use ctrl F to find the following code
<b:widget id='Attribution1' locked='true' title='' type='Attribution'>
- Replace true with false and save your template.
This would be that
<b:widget id='Attribution1' locked='false' title='' type='Attribution'>- Now go to "Page Elements" and edit "Attribution" at the button of your template layout.
- Click the "Remove" button from the pop-up window as shown in the image above
- Click "Save" and you are done, check your blog and found the blogger attribution disappeared.
- Just remove default attribution widget and add a custom one.
Option 2:
Go to blogger and click CTRL +F to find </head> tag
Next code paste just above </head> tag:
<style>
#Attribution1 {
display: none;
}
</style>
Save your template and that's all.
I am truly hope that works fine.
Happy Blogging