Oracle - Delete dmp files from ASM diskgroup
Just did a small test.
# find some ASM files
asmcmd find DATA/T101N/AUTOBACKUP/2020_09_20/ \*
+DATA/T101N/AUTOBACKUP/2020_09_20/s_1051641713.313.1051641713
+DATA/T101N/AUTOBACKUP/2020_09_20/s_1051658719.331.1051658719

# remove them one-by-one
asmcmd rm DATA/T101N/AUTOBACKUP/2020_09_20/s_1051641713.313.1051641713
asmcmd rm DATA/T101N/AUTOBACKUP/2020_09_20/s_1051658719.331.1051658719

# they are gone
asmcmd find DATA/T101N/AUTOBACKUP/2020_09_20/ \*
ASMCMD-8002: entry 'AUTOBACKUP' does not exist in directory '+DATA/T101N/'

Your scenario should be similar:
#!/bin/bash

# set grid home
. oraenv &lt;&lt;&lt; +ASM

# delete dump-files
asmcmd rm -rf DATA/EXP exp\*.dmp

Best of luck!