How should I handle two green card applications?

You can cancel it after the final approval from USCIS on the EB-2 adjustment, but there is no harm in keeping it there and waiting until that happens.

It is always best to notify them so they can clean up their records. Send a letter that you will not need this to NVC (or USCIS if not approved) with a copy of your green card.

It would be courteous to cancel the family petition. However, if you might at some time surrender your green card, the family petition could be used as a fallback solution.

If the I-130 is still pending with USCIS, it is up to the petitioner to decide whether to withdraw the petition. If it is approved and you are awaiting the priority date to proceed with visa processing, you can notify the National Visa Center; however, currently, they are not really responding to non-emergency communications. You are not obliged to notify NVC until the case is assigned for visa processing. If you do nothing, it will terminate after a year of inactivity.

Generally, once one of the two green card applications is processed and approved. The second application will be canceled.

If you obtained your green card, then you do not have to cancel the other petitions as they will automatically cancel.

No action is required.

Either is fine but I would cancel it since you already immigrated and got the green card.

You can cancel it, or you can leave it as is. Perhaps you will need it someday.

You should notify the national visa center that you adjusted status as a permanent resident and include a copy of your green card. You can use the National Visa Center Public Inquiry form online.

You don''t need to cancel anything, but the U.S. citizen petitioner (your sibling) could request to withdraw the petition since it is no longer needed.