This article will teach you how to remove a border line in Microsoft Word that may have been created by accident by entering three hyphens (-), underscores (_), equal signs (=) or asterisks (*), and then pressing the "Enter" key.
Steps
Method 1 of 3: Highlighting and Deleting

Step 1. Click on the line just above the desired line
If there is any text above the line, select the line above it.

Step 2. Drag the cursor to the line above the unwanted line
The left end of it will be highlighted.

Step 3. Press the Delete key
In many versions of Word, doing so will remove the line.
Method 2 of 3: Using the "Home" Tab Shortcut

Step 1. Click on the line just above the desired line
If there is any text above the line, select the line above it.

Step 2. Drag the cursor to the line above the unwanted line
The left end of it will be highlighted.

Step 3. Click on the Home tab at the top of the screen

Step 4. Click on the "Borders and Shading" button
It has a four-part square icon in the "Paragraph" section of the ribbon.

Step 5. Click Borderless
The border line will disappear.
Method 3 of 3: Using the "Page Borders" Dialog

Step 1. Click on the line just above the desired line
If there is any text above the line, select the line above it.

Step 2. Drag the cursor to the line above the unwanted line
The left end of it will be highlighted.

Step 3. Click on the Design tab at the top of the window

Step 4. Click the Page Borders button in the upper right corner of the window

Step 5. Click on the Borders tab at the top of the window

Step 6. Click None on the left pane

Step 7. Click OK
The border line will disappear.