What is a document map?
Document Map comes handy browsing large documents in Word. The feature creates a list of all headings and sub headings and displays in a separate pane.
How does Document Map help you?
You can quickly jump from one heading/subheading to another. Saves you from tireless browsing to get to a specific section.
How does Document Map work?
Word creates Document Map based on the heading styles applied in the document. Therefore, use built-in heading styles.
Note: To know how to apply built-in heading styles in your Word document, read the following article:
https://wordknowhow.wordpress.com/2013/05/20/how-to-fix-multilevel-list-in-word/
When you click an entity from the Map, Word brings up the corresponding section of the document to the top.
How can you view Document Map?
From the Word Ribbon, click tab menu View.
From the group Show/Hide, click select check box Document Map. Word displays the Document Map pane on the left.
You can expand a heading level in Document Map to view its sub headings or collapse to hide all. Right-click anywhere in the Document Map pane, select a heading level. Document Map pane displays headings till that level only, e.g. if you select heading level 5, Document Map pane will display heading 1 through heading 5.
How will you fix Document Map to remove unwanted entries?
Click the unwanted entry from the document map. Word places the cursor at the beginning of the corresponding heading/body text in the document.
Now, select the heading/body text and then right-click.
From the right-click menu, click Paragraph. The Paragraph dialog box appears.
On the Paragraph dialog box, under the tab Indent and Spacing and within section General, view the field Outline Level with a drop-down list.
Now, select the outline level as Body Text from the drop-down list. The content will no more be part of Document Map.
MS Word Know How 
Does anyone know how to change the background color in Word 2007 Document Map? I’m a novelist and would like to cut down on the high contrast. Help, please, if you know. Thanks.
Is there really no way to create document maps within tables?
How to delete document map setting in word 2007?
Sorry, I did not get your question properly. If you are asking how to delete a Document Map, then the answer is, you cannot, but you can hide it by clicking the “Document Map” check box in the View menu (View >> Show/Hide >> Document Map). Document Map is a built-in feature in Word. It uses the Outline levels in a document to create an index map.
If you want to control what should and what should not appear in the Document Map, you need to change the Outline Levels of the paragraph, headings, etc.
Suppose, you do not want a heading or a text line to appear in the Document Map, then
1. Select the heading or line of text first in the document.
2. Right-click and then select Paragraph from the right-click menu.
3. Under Indent and Spacing tab, in the Outline level drop-down list select option Body Text.
Is there a way to display the document map by default when in page layout view?
You can…on the ‘View’ menu, within the group ‘Show/Hide’, keep the ‘Document Map’ check box selected. All your documents will now the show ‘Document Map’ pane by default.
Hope this clears your doubt.