How do I remove scrolling from the cursor keys which was recently applied after downloading an 'Add-on'?

I recently downloaded an add-on called 'easy scroll' or something similar. It has meant my cursor keys now scroll up and down in the browser. However I use a web application that requires the use of the cursor keys to select options not to move around on the page. Can you tell me how I can reset scrolling to not use the cursor keys? Thanks.