Can I free up space by removing submissions?

When the 100 MB space limit is reached in the Free account, can space be freed up by downloading the oldest submissions and then deleting them from the account?

100 MB space limit is related to upload space, meaning only deleting submissions with file attachments on them will free up this space.

Submission storage is limited to 500 submissions for free accounts. These are the most recent 500 submissions you have received. Older submissions are being deleted after receiving more than 500 submissions. You can also delete your submissions to manually free up this space.

You can check this user guide to have more detailed information about account limits.

I hope this helps.