can i flush?

That depends on what your growing in and how heavy you have been feeding her. "Flushing" has been proven to not be needed when a plant is fed correctly. But if you insist then. Your buds look nice, the tips are slightly burnt but nothing major. It almost looks like your in living soil which does not require a "flush". If you are using bottled nutrients then you will want to reduce your feed by 50% or more near the end to ensure you don't have any buildup. When you grow you want to keep track of what the manufacture says for "Flower" time or grow time as they are usually very accurate. RQS says your strain would take 10-12 weeks. I'm guessing your on week 9.