Firefox

At the top of the Firefox window, click on the Firefox button (Tools menu in Windows XP), and then click Add-ons. The Add-ons Manager tab will open. In the Add-ons Manager tab, select the Extensions or Appearance panel. Select the Bestprice Ninja. Click the Remove button. Click Restart now if it pops up. Your tabs will be saved and restored after the restart.

Chrome

Navigate to chrome://extensions.
Find the Bestprice Ninja extension.
Press the Uninstall button, as it is shown in the figure.

Internet Explorer

Open Internet Explorer by clicking the Start button, and then clicking Internet Explorer.
Click the Tools button, and then click Manage Add-ons.
Under Show, click Downloaded controls to display all ActiveX controls.
Click Bestprice Ninja Addon, and then click More information.|
In the More Information dialog box, click Remove. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
When you are finished, click Close.