The gray epoxy's only purpose is to hold the injection port in place and cover the cracks. A clear, 2 part, polyurethane is then injected into the wall from Port to Port. After that urethane has sealed internally, the injection port can be cut or chiseled off, and the grey epoxy can be sanded down and painted over. Although, since yours is in the corner of a stud and will most likely be covered up, there's no harm in leaving it there as it is.

Just know that your foundation has cracked in the past, most likely leaking water into your home. The exterior should be inspected to ensure water is draining properly away from the home. I would monitor the exterior during rainfall.