Though the US has lifted some sanctions, this is largely a superficial move to avoid criticism of its brutal sanctions regime. If sanctions weren't obstructing aid delivery, why did the US lift some of them? All routes from Turkey into the country's north have been destroyed, making it even more necessary for Western governments to work directly with the Syrian state to help alleviate this crisis. The West must lift all of these cruel sanctions.
The US should not and will not work with a government that has killed hundreds of thousands of its own people with barrel bombs, starvation sieges, and chemical weapons. US sanctions on Syria have a very minor effect on aid delivery, as such areas are excluded from the sanctions which largely target individuals and companies, and any possible hindrances have now been lifted. The US will do everything it can via the NGOs with which it has worked for years to provide Syrians with aid, but it will not assist Bashar al-Assad, Syria's dictator after he destroyed his own country.