1. Go to Blogger Dashboard --> Template
2. Please! download a copy of your template
3. Now click on Edit HTML
4. Use Ctrl+F to find Attribution
5. We change the option 'true' to option 'false' ( Look the screen )
6. To become like this <b:widget id='Attribution1' locked='false' title='' type='Attribution'>
7. Finally click on Save template
Now go to gadget which you want remove it.