Thanks kidace. This worked for me, but I don't show any prices at all so I left it on variable.
I tried switching as you said from simple product --> variable --> then back to simple. When set to variable, the sale tag disappeared from the product. Then when set back to a simple product, the Sale tag reappeared.
Odd. This works for me because I don't show any prices at all, so I am just switching all my products to variable.