That has to do with how you have configured your STYLES (if you used them at all) within your document. If you are not familiar with STYLES, here are some links that can help you:

Understanding styles | ShaunaKelly.com
Understanding Styles in Microsoft Word

To quickly remove, or reconfigure the style of the hanging indent, right-click in the paragraph in question and from the subsequent menu, select PARAGRAPH. Then, from the resulting menu in the INDENTATION section (mid-menu), make your adjustment to the desired level (if any).

After making your adjustments (and, if needed, refer to the link(s) provided)....READ the links for a better understanding. The payout is well worth it...an hour or two will save you multiple of hours down the road.