Can I delete an Oracle “Whole database backup” while a level 0 backup is being created?

I have created a Whole database backup using:

-- In SQL*Plus
ALTER SYSTEM SET DB_RECOVERY_FILE_DEST_SIZE = 5000G SCOPE=BOTH;
ALTER SYSTEM SET DB_RECOVERY_FILE_DEST = 'O:ORA_FRA';
alter system set db_create_file_dest = 'C:ORADATAMAINDB';
alter database enable block change tracking;

-- In RMAN
configure default device type to disk;
configure device type disk backup type to backupset parallelism 1;
configure backup optimization on;
configure retention policy to recovery window of 31 days;
configure archivelog deletion policy to none;
configure controlfile autobackup on;

Backup database plus archivelog;

This backup finished. Then I realised I actually needed a Level 0 incremental backup. I started this using:

run
{
    allocate channel disk_iub device type disk;
    recover copy of database with tag daily_iub;
    backup incremental level 1 for recover of copy with tag daily_iub database;
}

This backup is now in progress, but I am afraid the Fast recovery area will run out of diskspace with the former whole database backup still stored there.

Can I safely delete the first backup? If so, how?
Or, will I somehow run into problems with the archivelog and block change tracking?
I’m aware there will temporary not be a usable backup. That is acceptable, as I have a data-dump somewhere else.