I used salted butter in my SMBC and I can really taste it. What can I do to help the flavor? I've added vanilla, I've even added some powdered sugar, but it still tastes salty. Thanks for any help.

I use the same brand of salted butter in my icing, but never do I add any additional salt. If it is too salty, I would start over...Try making some new without the salted butter and mix 1 cup of the unsalted with 1 cup of salted...see if that takes it down a notch or two...if not, mix it 2 to 1, etc.
If not, then ...use the too salty butter cream for the decorations and for attaching the cake to the cake board, etc.