There is currently no way to delete a custom EasyApache 4 profile via WHM.
Fortunately, they're easy enough to remove via SSH by navigating to the /etc/cpanel/ea4/profiles/custom/ directory where you'll see a list of custom profiles:
root@server [/etc/cpanel/ea4/profiles/custom]# ls
./ ../ ea3_state_at_migration-1473095302.json
You'll need to inspect the contents of the file in question to ensure you're deleting the intended profile.