You don't need to worry as the plant will be fine, even if you do nothing, but you can knock the larvae off the plant if they are bothersome. These are the larvae of the aptly-named Hibiscus Sawfly, a common insect. Management options are given in the linked page, and the simplest approach is to manually remove them using fingers to flick or squish them, or plain water from a garden hose spray to blast them off of the foliage. If needed as a last resort, a couple options of low-toxicity insecticides can be used to carefully spray the foliage, on both the upper and lower leaf surfaces.

We usually don't see this native pest until a bit later in summer, but perhaps the plant shipped to the retail nursery from a location where they have already hatched. (We're not blaming the nursery for shipping plants with pests, as eggs or very young sawfly larvae would be very hard to detect. Plus, their presence suggests the plants were not being treated with broad-spectrum insecticides, which is a good thing.)

Miri