I have removed the shanks on buttons to make earrings and most of the time they come off nicely. there are nice fabric glues that will hold through any washing. If the shank doesn't come off clean I have used side cuts from the tool box to clean then up and sometimes I heat up a flat tool to melt them flat or sand them down. I would do that but I know there are others that would like it hanging loose. It is your decision. I would think it they were hanging loose they may be caught on something and rip off. Lots of ideas here.
Lynda