The first step to take to remove oven cleaner from granite is to simply try and remove as much solution as you can, as soon as possible. You can do this with any absorbent tissue but be careful to use protection on your hands. Another effective solution can be to pour some vinegar on the oven cleaner. The cleaner will be a heavy alkaline solution and the acid from the vinegar can help to neutralize it. When you've removed it, make sure to wash the surface with a regular countertop cleaner. If you find that the granite has been stained then it may not be the actual stone itself that has been stained, rather the sealant that's applied over it. If you have a stain that simply won't go away then you may need to reseal your countertop.