I’m a green card holder since two years now. I obtained my green card through my uncle (who had sponsored my father). Can my uncle withdraw his sponsorship and get our green cards revoked?
In general, once resident status (green card) is issued based on an approved visa petition, the immigration process has been completed and the petitioner (your uncle) has no legal authority to revoke it. One exception may be in marriage cases where resident status is “conditional” and it is reported to immigration that the marriage was not bona fide, and solely for immigration purposes. Your case, however, appears to be based on a sibling relationship, so I assume that your resident status (green card) is not conditional, but permanent. It thus cannot be revoked by your uncle.