There is a quota on your home directory that is intended for storing results. ComputeSpace is not intended for storage. It is a storage space for the duration of your calculations. The quota command lets you check your disk usage.

Tips for cleaning up

Detect / delete duplicate files

fdupes . -r -d is a command that lists duplicate files and offers to delete them as desired.

Use ncdu to check disk space usage!

When connected to a terminal, ncdu is a command that lets you visualize disk space usage in your directories and even clean up files.