Navigate to the Site or Subsite that contains the list or library that you would like to edit.

Once there, select "Site Contents" and find your list or library and select the ellipses next to it and select "Settings".

Click on the column you would like to remove and select "Delete"

Now that you have removed the column from your list or library, you can access your K2 artifact page and you will get an option to "Regenerate SmartObjects" or "Regenerate SmartObjects, Forms, or Views".

Select only SmartObjects if you have a lot of custom rules, or styles already in place on your form.  If you can replace all of that fairly easily, you can go ahead and regenerate your views and forms too.

If you only select to regenerate SmartObjects, then navigate to the Layout tab of your view and manually upload your column either by removing one and dragging the property over, or selecting "Create Labels and Controls" (You will lose custom styles with this option).