Follow these instructions to clear background color of cells and textboxes in Excel spreadsheets:
Excel 2003 or earlier: Use the background colour selection tool on the Formatting toolbar:
Excel 2007 or later: Select the cell(s) or textbox(es), and use the background colour selection tool located in the Font group of the Home tab:
Alternatively, you can also accomplish the same as follows:
Excel 2007 or later: select the cells or textboxes you would like to format, right-click and choose Format Cells... or Format Shape... / Format Object..., respectively. (There are other ways to do this, so look around Excel).
Format Cells dialogue: choose No Color under Fill tab:
Format Text Box dialogue: select Fill from the list on the left, and select No Fill as shown below:
Excel 2003 or earlier: select the cells or textboxes you would like to format, and click Format -> Cells... or Format -> Text Box..., respectively. You can also do the same by right-clicking and choosing Format Cells... or Format Text Box...
Format Cells dialogue: choose No Color under Patterns tab:
Format Text Box dialogue: select Colors and Lines tab, and then select No Fill from the Color list as shown below: