How to delete unwanted stored solutions?

Hello,
I am simulating large 3D RF problem in time domain in version3.5a. And I found my whole stored file is as large as 40GB, since I stored around 600 time steps. And I want to delete the last 100 time steps to save some memory of the server without recalculate the whole process.

I would be very happy if someone knows how to do it.

Best wishes,