You're not going to like this, but you'll probably have to wait 4-6 weeks for that flavour/smell to go away. I had 2 beers with this banana taste (notty yeast and S05). One of them mellowed out sufficiently, the other mellowed out but it still bothers me.
You fermented at too high a temperature. I've recently had success fermenting in my cold cellar, where the temp is usually hovering around 50-55F. This seems fine for that initial blast of fermentation. Here's my exact process:
-boil and cool wort.
-pitch yeast @ around 70F (after whirlpooling cooled wort in 70F basement)
-stick the bucket in the cold cellar, ambient air temp is 50-55F
-come down the next morning, see airlock bubbling away nicely, smile to myself
-do nothing for 2 weeks
-check gravity, adjust for temp.
-if gravity is at expected FG, I'll take the bucket out of the cold cellar for a couple days.
-if gravity seems stalled at something higher, I'll take the bucket out of the cold cellar for a week.
-check gravity again, then throw the bucket back in the cold cellar on a shelf and leave it until I've had 4 weeks of total primary action.
-when it's time to bottle, I siphon from the elevated primary that's been sitting there untouched for about 2 weeks. Beer is super-clear, and I bottle it cold-ish.
Success!
Bottom line: until you get your fermentation temps down, you won't have great beer. I'm finding it's better to have them too cold rather than too warm. Worst case scenario if it's too cold: yeast go to sleep, but you can easily wake 'em up. Worst case scenario if it's too warm: weird off-tastes and your beer isn't as good as it could have been.
Cold > Warm. Always.