P4ROOT
is on the server, so if you're connecting to a remote server, you need to contact the admin of that server and let them know that it's wedged. Your workspace specifically is not the problem, the overall lack of space on the server is. All that needs to happen to fix it is increasing the available disk space. (Deleting your workspace would free up a little space on the remote server by pruning the associated db entries, but those are very small compared to the depot files.)
The "requires 2G available" thing is because by default the server looks for an available 2GB of empty space before it starts any operation; that's to provide reasonable assurance that it won't run out of space completely during the operation, since actually hitting a hard limit can be hard to recover from (db tables might be in a partially-written state, etc).
If the admin wants to try fixing this by obliterating large files (this is usually a pain and I'd recommend just throwing a bigger hard drive at the problem instead), they can temporarily lower that threshold to be able to run the obliterate, but I'd recommend bumping it back afterwards.