There was a thread where this was discussed four months back.
The primary Applicant cannot revoke the GC of the spouse.
If the Spouse is waiting for GC, the I485 application may be withdrawn.
There is also thread where someone got divorced with a week of spouse receiving the GC.
He wanted to find the options. It was concluded unless there is a solid evidence that can prove that the spouse had a premeditated plan to divorce after GC, It will be difficult to revoke the spouse's GC.