first you will not be able login for database or rman
-Go to archivelog detestation and delete archivelog (old first) , if you have space on your server you can move them from direcotry to another .
-Flash Recovery On ASM , Follow the below steps
now you are inside ASM head to Archivelog destation and delete archive log manually (old first )
Step 2 :
Now you will be able to login to rman :
ALLOCATE CHANNEL c1 DEVICE TYPE DISK FORMAT '/u01/';
backup archivelog all delete input ;
release c1 ; }
Now you clean Archivelog .
THis solution for Both Cluster and Single Node Database