Lumpy forehead and it's been 2.5 years after I've injected "Ellanse S". Can these holes only be removed surgically? (Photo)

PolyCaproLactone is the "active ingredient." It is suppose to be a biodegradable polyester. Unfortunately the microbeads get walled off and persist. This material is organized into scar tissue. Removing it is very challenging without causing scaring. Your forehead lump is close to your hairline. It should be possible to approach this mass from a small incision behind the hairline. It may be possible to debulk this mass caused by this terrible filler. 

It is very likely that your filler is encapsulated and mostly replaced with scar. One could consider injection of corticosteroid (Kenalog) to diminish the scar but surgical removal may be a more predictable solution. This "lump" can be remove/shaped through hairline incision in local or twilight anesthesia. Good luck.

Your pictures shows a persistent lump on the right side of your forehead which I presume is a collection of the injected material. Given that the injected material was a polymer and now encapsuled by scar tissue, trying to suction this areas is not very likely to be successful. Surgical excision would be the only effective treatment. A hairline incisional approach would be used to approach. The biggest risk is trying to get the material/scar out without causing other forehead contour issues. (irregularities or an indentation)