well even you are in archive mode you must take hot backups, once you have a hot backup set the archive logs generated before the hotbackup can be deleted.
But it's always advisable keep one or two weeks logs
If you have backups that are newer than archives, I don't see any problem in rm the archives. However, storing the archives in another media instead of simply removing them may be a good idea. You don't know if tomorrow your boss will ask you to recover the database X to day Y, hour Z.
best way to over come that type of situation is just move arch files(keeping last 2/one week files depending upon the growth rate and space availability) from that dir to some other directry where you find space to keep them(say some dump01 dir).keep it for 2weeks and delete them.That way we can have total 4 weeks of log files always.compress if you have space constrains.Also ensure you are monitoring daily and doing so....I am following the same principle and it is working....