How do you remove rough edges from completed prints?
To remove unwanted residual material:


You can scrape with a knife
Use sand paper
use files
Very fine sandpaper or files can smooth out the rough surfaces left from filing or sanding.
Dremel tools tend to be aggressive.  They tend to melt the surface if too fast.  Buffing wheels are probably the most useful on a Dremel.  Dremel tools are good for cutting.


A deburring tool can remove sharp edges such as parts of the brim that don't want to come loose.  However, it's not unusually to need to scrape off flat surfaces as well.

If you want to smooth out the surfaces left from layers, you can:



Carefully use a heat gun or heat from other soldering tools; not spending too long in one spot.  The difficulty with using heat is most prints have fill rather than being solid; so, with only two or three outside layers, it's easy to get the surface to deform into the fill. Also the print material will tend to stick to solid surfaces hot enough to melt the material.
Use acetone on ABS.  Don't breath the fumes or dissolve your print.
Paint the surface as the comment from user77232