Imgur links automatically use the embed mode and there is no option to disable this feature.
However, there are workarounds you can do to prevent this.
If you want it to show as a link, you can use the "Insert link" feature instead of directly posting the link. This will prevent the link from being changed to a media object.
Link to image page
Direct link to the image file
A bit more complex, but you can also make a custom thumbnail by putting the image inside an img tag, then putting all that into an url tag:
Code:
[URL='LINK_TO_IMAGE_PAGE']Link to image page[/URL]
[URL='LINK_TO_IMAGE_FILE']Direct link to the image file[/URL]
Clickable thumbnail:
[URL='LINK_TO_IMAGE_FILE'][IMG width="150px"]LINK_TO_IMAGE_FILE[/IMG][/URL]