Apply or remove indent from the Ribbon in Excel 2007

When you apply the indent, the text gets displayed away from the border of the cell. In other words, you are increasing the margin between the border and the text in the cell. To apply the indent, on the Home tab, in the Alignment group, click the Increase Indent command.
On clicking the Increase Indent command repeatedly, the text moves farther away. If the text is wrapped then the data in all the lines move at the same time.

Keyboard shortcut:
Press CTRL + ALT + TAB

Remove or decrease the indents:
On the Home tab, in the Alignment group, click the Decrease Indent command. On clicking the Decrease Indent command repeatedly reduces the indent level.