This tips work for the new blogger template design.
1. Login to the blogger design page click on "Post"
2. Tick / Select any post that would like to remove the label. In the image example, we want to remove the "Movie Review" label.
3. Click on the "Label" icon tab. Then select "Movie Review", this will remove the label from the blog post. You can add another label by selecting from the list.
4. That's it.
5. Note that if the label is not associated / link to any posts, it will automatically removed from the list. You cannot retrieve it, but can re-create new when posting new blog's contents