Hi,
Make use of Replace function in When function. Case(When(check for substring to see if you have a tag, use replace function here), Else(use original product name if you don't have tags))
Example:
Case(When(Left(ProductName, 1) = '<', Replace(ProductName, '<span class="xxx">xx</span>', 'xx')),Else(ProductName))
I have used something similar to the above earlier. you can make use of it.