If you inadvertently spray an area with a vegetation poison is there anything you can add to the soil to neutralize the effects of the glyphosphate (5%) so that you can plant shrubs?
Unfortunately not. This product is intended for use on hard paved areas or areas where nothing will be grown for up to a year. In a very wet climate, the residual effects may pass in 6-9 months, but otherwise, its a year. It contains imazapyr as well as glyphosate. It is not even recommended for use on a sloped path, because of the risk of run off onto planted areas.
If you sprayed rather than watered it on, the effects might pass sooner, but without planting something in the area in, say, 3 or 6 months, and waiting to see if it dies, you won't know if it's cleared or not, other than watching for weed germination.
Glyphosate is not a residual herbicide, ie it doesn't prevent weed seeds from germinating. So the glyphosate content of Ground Clear isn't your problem. The problem you have is caused by imazapyr, the other active ingredient, which is residual. If it was me, I'd put it down to experience and wait a year or, as Bamboo says, wait for healthy weeds to appear before planting.
Glyphosate is not the big bad chemical it is being made out to be. But this Ortho product you used is not just glyphosate. It is formulated to kill weeds, weed seeds (preemergence) as well as any plants you want to plant in that soil for an entire year. Forget trying to remove the soil. Using just glyphosate that chemistry changes the instant it is sprayed on anything. It does not leach. There is a period of time where no seeding or planting should be done for 3 weeks. Not an entire year.
You have to wait an entire year. You might try contacting Ortho and make sure to share their recommendations with us before you buy or use any more products. I have to remind you, pesticides are never ever necessary. Fertilizer yes, but not fertilizer with pesticides/herbicides.
Where is this area? Might be a great place for a gravel patio?