SQL Out of space

When Sysaid was installed it was installed using SQL Express, we've just ran out of space.
Is there a way to filter by attachment in Sysaid. Were looking at removing some of our old customers who have long since gone. I'm staying away from that shrink button so think this would be the next best logical step.

Any other suggestions would be great, we will not be investing in a full SQL licence as i doubt we will be staying with the Sysaid product forever.