How do I remove part of a tag

How do I remove part of a tag after a certain character. For example, this is what the artist tag is currently set to:

Oceanic / Insanity
Blue Pearl / Naked In The Rain

What I want to do is delete all characters before the /, so I'm left with just 'Insanity' and 'Naked In The Rain'. Is this possible?

I do not think this is possible because every song name contains different types of words before the / and a different amount too.

Sure it is possible.
One way:

Action type: Guess values
Source format: %artist%
Guessing pattern: %dummy% / %artist%