I'm a former realtor and my advice is DO NOT CLOSE PERIOD!!! Having been a licensed realtor, your agent is telling you to close but hold back the money because 1) he/she wants to receive their commission check and 2) the title / deed can be registered with the county making you the new owner.
This is a very bad deal for you because ...
1) If the title / deed passes from the current owner to you, then all rights and responsibilities of owning the home is on your shoulders. Therefore, ALL the garbage will be your responsibility and the owner doesn't have to get rid of it.
2) The realtors don't care (including yours) because once a real estate transaction closes, they have no further responsibility to do anything. Meaning they don't have to get involved and their advice will be:
"I'm sorry but since the transaction closed and you're the new owner, you need to contact an attorney. I can recommend one and here's the phone number."
To repeat - once you close, the house and all the responsibilities are yours. Do NOT listen to your realtor. You have every right to delay the closing until ALL the garbage is thrown out. Your agent can wait a few days to get paid. If your agent gives you a hard time, tell him/her "too bad. They are not paying your mortgage, property taxes and insurance."