Where are you trying to edit this hole? In Part environment or in an Assembly? And with which options is this hole created (assembly feature, asembly-driven part feature, create part feature)?
Example:
1. open assembly
2. select Hole command
3. select Create Assembly-Driven Part Feature
4. place holes on the parts in the assembly.
Now, if you open any of the parts from this assembly, you will see the holes. But they are created at the assembly level, therefore you can not edit those in the part. If you want to change those holes, you have to open assembly and check the Assembly-Driven part features in the Assembly Pathfinder. There, you will see your hole and you will be able to edit it.
If you have a different problem, can you attach an image (which edit icon is gray, etc.) or a movie showing the problem?