To reset your image back to its original size and dimensions:
Scroll down to the Create your website section and click on the Website Builder icon.
Click on the Login button next to the relevant package.
In the Design view use the mouse to click and highlight the image you wish to reset.
Click on the cog icon to open the settings menu for the image.
In the Image menu that appears at the bottom of the page, click the Reset icon.
Your image will now be reset to its original dimensions.