How can I edit labels on multiple posts at once -How To Deleate Label

The Edit Posts page includes options for displaying posts by label, and for applying or removing labels on batches of posts. To get there, visit the Posting | Edit Posts tab, or just click the Manage Posts link on your dashboard.
This page has all labels in use by this blog listed on the left-hand side. Each individual post also has its particular labels marked in green next to its title. By default, posts with all labels are shown.
(Note: You'll only see the labels here if you have at least one post already labeled. You can label an individual post on the posting form.)
If you click the label links on the left-hand side, the list of posts will be narrowed down to show only posts with that particular label.
Each post has a checkbox next to it. If you want to make a change to multiple posts, first check all the ones that you want to affect. Then select an option from the "Label Actions..." menu.
This menu includes options for adding any of your labels to the select posts, as well as for removing labels already on the posts. You can also select "New Label..." if you want to create a label that you don't already have.
If you want to edit a label across all posts, you can do so by removing it and then adding a new one. For instance, say you want to change the label "Books" to "Reading." Just follow these steps:

1. Click the "Books" label link on the left side of the page.
2. Click the "Select All" link at the top of the list of posts.
3. From the "Label Actions..." menu, choose "Remove label > Books."
4. From the "Label Actions..." menu, choose "Apply label > New Label..."
5. Enter "Reading" as your new label. (If you already have some posts with the label "Reading," you can simply apply that label, without making a new label.)