Well, not strictly true. In the last few years stent removal has become more common. For example, one patient had their entire LAD stented from top to bottom and a bypass was required because of restenosis. The lower stent was removed to allow grafting of the LIMA to the LAD and this was done using an arterectomy. 18 months after the procedure, the flow is still very good.
Stents can't be removed. The only option would be removal of the entire artery, I think, but I'm not a health professional. Since you have had a bypass, the plugged artery/stents are just along for the ride, neither helping or hurting.