Splicer, multiple fields remove blanks

Hi there, I have a collumn for that lists the College a row is for:

However, the College of Science is split into further streams in another collumn:

The row values which are not within college of science are null.

Using this information I want to create a splicer, with a dropdown to select the different streams of College of science.

My question is, is there a way of remove the (Blank) value within the colleges that are not College of Science?

Thanks