Prune RRD data

[EddieA]

Is it possible to remove part of the RRD data.  For some reason, when I first started my pfSense nano image box, it recorded an incredibly high traffic rate, which means my 6-month and year graphs are scaled in such a way that I can't really see much usage:

Is there a way to remove the offending entries, or do I have to blow away all the data, and start again.  If the latter, how is that achieved.  Will deleting the /cf/conf/rrd.tgz file and rebooting do it.

Cheers.