Do you want want to remove all borders on your image? You can use the CSS tweaks in Canvas theme. Please refer to the steps below

Prerequisite(s)
Canvas theme
Canvas child theme


Step 1 Login to your WordPress control panel

Step 2 Provided that you have already uploaded a Canvas Child folder containing style.css and functions.php files in the themes folder using FTP. Go to Appearance > Editor

Step 3 Enter the following codes in Canvas Child’s style.css file

/*
Theme Name: Canvas Child
Theme URI:
Description: Child theme for the Canvas theme
Author: Jezweb
Author URI: http://www.jezweb.com.au/
Template: canvas
Version: 0.1.0
*/

@import url(“../canvas/style.css”);

.entry img, img.thumbnail {
background: none;
border: medium none;
padding: 5px;
}

note: We are using a Canvas child theme so that your CSS settings will not be changed if there is an update with the main canvas theme.


Step 4 Click Update File and go to your online site. Image border should no longer be visible.