Set expiry time to remove entries from DB

I have a client site that has a few contact forms in place where visitors upload documents.

Over time, around a year, this has amounted to a total of 1.2GB in uploaded files and the site is getting busier.

Is there an add-on or any way to automatically set entries to be removed after setting a period of time, say around 6 months?

If not, is there a way of displaying file size in the table of entries so my client can pick out and order the entries by file size to remove the heaviest files?

Thanks.