As one one of the Admins on this forum, I can tell you that I have personally cleaned up space on the attachments by deleting the largest attachments on occasion.
At one point, this Web-Host and account was also used for the xLights releases. When the disk space consumption was full, the xLights download page would go offline as there was not enough room for the log files for the website.
Now that Sean has moved the xLights page to it's own account, the Forum here should be able to accommodate long term attachments. Many were non-useful to anyone but the uploader and a developer for help. No need to keep those around. Sure a few screenshots got caught in the crossfire.
-Steve