On most configs you need to be in root to access delete things in pine.
Once you are in root you can just view messages and then go down the line and delete them.
When it gives you the locked message that means its really full, a little icon should be rotating while it loads them all up.
Im not sure why its giving a out of memory error, check your var to see if its at 100%, if so delete unwanted files from there (make sure ya know what you are deleting)
