See → FAQ: How can I reduce quota usage while still retaining prior work (data, tools, methods)?
You will need to backup your older work, then purge it off the server to make room for new work. If you export your history to a file (archive – see the history menu for this option), later you can import it to work with it. The exported history archive file will have a URL so could go anywhere where you have cloud storage, or you can download it to your computer.
You didn’t state where you are working, but if at UseGalaxy.org there is a new “scratch storage” function which grants 1 TB of temporary working space (30 days) along with the default 250 Gb of permanent storage.
Screenshots of where to set this under User → Preferences → Preferred Storage Location. You will need to be under quota for the permanent storage before more jobs will run into either of these spaces.
To move individual files between storage locations, click into the “i” icon and see the link to the toggle switch.
Some more is in this prior post → What is scratch storage?
Once the new functions are fully deployed, we’ll have more documentation. Right now we are still testing it … but you can certainly use it.
The final option is that if you are an academic researcher, and need space for some larger project for a few days or weeks, you can ask administrators of the server where you are working. Some have a quota request form – UseGalaxy.eu has this on their homepage, and others can be different (you need to write in via email). See the Galaxy Directory here → Public Galaxy Servers
If you can’t find the contact for some server, you can post the server URL and we can try to help more here.
Hope this helps! 