Okay let's check the step below to start removing the widget from your blog:
Step #1: Go to you blogger dashboard>>>Navigate to Template/Theme section>>>Then click on HTML.
Step #2: Click the 'Jump to Widget' and select Attribution widget as shown in the diagram below. Note if you can't find it, use CTRL+F and find the Attribution keyword
Step #3: You will see these lines of codes and note the highlighted word.
<b:widget id='Attribution1' locked='true' title='' type='Attribution'>....</b:widget>Step #4: Changed the highlighted (locked) value from true to false, like this,
<b:widget id='Attribution1' locked='false' title='' type='Attribution'>....</b:widget>
Now go to the layout option, and click on Attribution widget, and you will see a removal option. Click on it to remove, and then save your settings.
Any problem? just hit me in the comment section.