Create a compute profile with two interfaces or volumes, then edit it, click the crosses and save. When you view the profile again, they'll still be there. Tested on libvirt + VMware.

The deleted entries aren't actually being removed from the hash before save. Instead, they're getting saved to the DB with _delete=1!

   (0.4ms)  UPDATE "compute_attributes" SET "vm_attrs" = '--- !ruby/hash:ActiveSupport::HashWithIndifferentAccess
cpus: ''1''
memory: ''805306368''
nics_attributes: !ruby/hash:ActiveSupport::HashWithIndifferentAccess
 new_nics: !ruby/hash:ActiveSupport::HashWithIndifferentAccess
 type: bridge
 _delete: ''''
 bridge: em1
 model: virtio
 ''0'': !ruby/hash:ActiveSupport::HashWithIndifferentAccess
 type: bridge
 _delete: ''''
 bridge: em1
 model: virtio
 ''1'': !ruby/hash:ActiveSupport::HashWithIndifferentAccess
 type: network
 _delete: ''1''
 network: hundred
 model: virtio
volumes_attributes: !ruby/hash:ActiveSupport::HashWithIndifferentAccess
 new_volumes: !ruby/hash:ActiveSupport::HashWithIndifferentAccess
 pool_name: default
 capacity: 10G
 allocation: 0G
 format_type: raw
 _delete: ''''
 ''0'': !ruby/hash:ActiveSupport::HashWithIndifferentAccess
 pool_name: default
 capacity: 10G
 allocation: 0G
 format_type: raw
 _delete: ''''
 ''1'': !ruby/hash:ActiveSupport::HashWithIndifferentAccess
 pool_name: default
 capacity: 10G
 allocation: 0G
 format_type: raw
 _delete: ''1''
image_id: /home/libvirt/foreman_template.img
', "updated_at" = '2014-06-06 17:49:46.519459' WHERE "compute_attributes"."id" = 4