How do I increase the limit for db_recovery_file_dest_size?
Answer:  Even though db_recovery_file_dest_size is 100%, deleting files from the directory was not the ultimate solution because I also had to update the RMAN catalog to remove the old redo log entries.
Also note errors/bugs in v$_flash_recovery_area.
The trick to increasing the limit for db_recovery_file_dest_size was to:
1 - Start the database, then mount the database (Do not open the database)
2 - Use RMAN to run a crosscheck on the archive logs and then update the RMAN catalog to delete the expired redo logs that I had manually deleted via the OS to free-up space in the disk filesystem directory.  See these notes on using the RMAN crosscheck command.
The following scripts will check space utilization for db_recovery_file_dest_size:
col name     format a32
col size_mb  format 999,999,999
col used_mb  format 999,999,999
col pct_used format 999
select
   name,
   ceil( space_limit / 1024 / 1024) size_mb,
   ceil( space_used / 1024 / 1024) used_mb,
   decode( nvl( space_used, 0),0, 0,
   ceil ( ( space_used / space_limit) * 100) ) pct_used
from
    v$recovery_file_dest
order by
   name desc;
*********************************
set lines 100
col name format a60
select
   name,
   floor(space_limit / 1024 / 1024) "Size MB",
   ceil(space_used / 1024 / 1024)   "Used MB"
from
   v$recovery_file_dest
order by
   name;